user1133: I am making a small video (not really a film) that has muffled/hard to understand dialogue. The video goes for about 2 minutes and I only need to subtitle roughly 2 sentences worth - so it's not a lot. 
I'm using Final Cut Pro 7 and I know how to insert text. What I need to know is what font is typically used for subtitles and what size should this font be?
Subsequently, if two people are talking simultaneously, what is the best way to alter the subtitle so the viewer is aware which subtitle belongs to which character?

user1890: Tips on subtitles.
1) make it clear, be sure the font color is not washed out by the background for instance don't put light lettering on a light background. In a word "contrast". Some title programs will have a shadow or outline to assist when the title is over a mixed light and dark area.
Choose an easily readable font. Consider why highway signs have certain fonts to optimize clarity.
2) make sure your subtitle is on long enough to read. The rule of thumb here and this pretty much goes for any title (exception being fast end credits) is read the title out loud, this will help you define the upper limit of how long to hold the title.
3) conversely, optimized subtitles do not overlap to the next shot as the eye will at first interpret this as a new subtitle. This falls under continuity.
4) Specifically for your situation where you are trying to make something clear in text that is not spoken clearly, consider a bit of editing to keep it concise as you may not
have enough time or room to subtitle the whole thing. This can be difficult as you don't want to be accused of 'putting words in someone's mouth'. On the other hand if you are looking for a comical angle, subtitles can be an effective tickler. Consider the effect of someone mumbling and the subtitle is constructed from a bunch of wingding fonts. Caution with comical intentions, in a world of 'politically correct' police, be sure this is in good taste.
5) There are many ways you can construct a dialog with subtitles. One way is to italicize the same font for the other persons subtitle. Or use the script like method Johnny Bigoode suggests, this is worth sandboxing until you find the best solution that works in the context of your video.
6) I agree with Johnny Bigoode as to allow for your creativity, if you get stuck, search around Youtube for videos with subtitles, ask yourself why some work well and others do not.

user2646: You can also left align the speech for person on left side of screen and right align for person on right side.  Or place the dialogue next to the person on screen.  I've seen this done a lot when TV sitcoms are subtitled, esp. when a scene has 3 or more people in a conversations.  Don't feel limited to the bottom third or center of the screen!

user1759: Subtitling is a horrible horrible thing, and there are loads of regulations and standards and other bull which can be found here. 
As for the font, it really depends on your opinion - if I'm not mistaken Trebuchet Sans and Deja Vu Sans are as close as you can get to the standard DVD fonts. 
But all I just said depend on your artistic point of view - if the subtitles makes part of the movie it shouldn't follow the general guidelines - I would strongly recommend using a font that makes sense with the movie (Example: Consolas would be great for a movie like Primer or Tron) and use free style subtitles - like the ones in classic adventure games. 
If you're not aware about these games, check out Full Throttle Opening on youtube.
Then again, here's some ideas about people talking simultaneously:
If they are from opposite sexes you can use different colors for each character. 
One character's lines could be on the right side of the screen while the other is on the left. 
You can even use different fonts (not recommended) 
But, according to the usual pattern you should identify the characters who are speaking with brackets and simply show both lines at the same time. 
[John Doe] I love you Mary. 
[Mary Doe] GTFO, I hate you. 

But, as mentioned before, I strongly recommend creating a unique style for your movie, specially since it's only a few lines. 

1133: <p>I am making a small video (not really a film) that has muffled/hard to understand dialogue. The video goes for about 2 minutes and I only need to subtitle roughly 2 sentences worth - so it's not a lot. </p>

<p>I'm using Final Cut Pro 7 and I know how to insert text. What I need to know is what font is typically used for subtitles and what size should this font be?</p>

<p>Subsequently, if two people are talking simultaneously, what is the best way to alter the subtitle so the viewer is aware which subtitle belongs to which character?</p>
 1890: <p>Tips on subtitles.</p>

<p>1) make it clear, be sure the font color is not washed out by the background for instance don't put light lettering on a light background. In a word "contrast". Some title programs will have a shadow or outline to assist when the title is over a mixed light and dark area.
Choose an easily readable font. Consider why highway signs have certain fonts to optimize clarity.</p>

<p>2) make sure your subtitle is on long enough to read. The rule of thumb here and this pretty much goes for any title (exception being fast end credits) is read the title out loud, this will help you define the upper limit of how long to hold the title.</p>

<p>3) conversely, optimized subtitles do not overlap to the next shot as the eye will at first interpret this as a new subtitle. This falls under continuity.</p>

<p>4) Specifically for your situation where you are trying to make something clear in text that is not spoken clearly, consider a bit of editing to keep it concise as you may not
have enough time or room to subtitle the whole thing. This can be difficult as you don't want to be accused of 'putting words in someone's mouth'. On the other hand if you are looking for a comical angle, subtitles can be an effective tickler. Consider the effect of someone mumbling and the subtitle is constructed from a bunch of wingding fonts. Caution with comical intentions, in a world of 'politically correct' police, be sure this is in good taste.</p>

<p>5) There are many ways you can construct a dialog with subtitles. One way is to italicize the same font for the other persons subtitle. Or use the script like method Johnny Bigoode suggests, this is worth sandboxing until you find the best solution that works in the context of your video.</p>

<p>6) I agree with Johnny Bigoode as to allow for your creativity, if you get stuck, search around Youtube for videos with subtitles, ask yourself why some work well and others do not.</p>
 2646: <p>You can also left align the speech for person on left side of screen and right align for person on right side.  Or place the dialogue next to the person on screen.  I've seen this done a lot when TV sitcoms are subtitled, esp. when a scene has 3 or more people in a conversations.  Don't feel limited to the bottom third or center of the screen!</p>
 1759: <p>Subtitling is a horrible horrible thing, and there are loads of regulations and standards and other bull which can be found <a href="http://www.ofcom.org.uk/static/archive/itc/itc_publications/codes_guidance/standards_for_subtitling/subtitling_1.asp.html">here.</a> </p>

<p>As for the font, it really depends on your opinion - if I'm not mistaken Trebuchet Sans and Deja Vu Sans are as close as you can get to the standard DVD fonts. </p>

<p>But all I just said depend on your artistic point of view - if the subtitles makes part of the movie it shouldn't follow the general guidelines - I would strongly recommend using a font that makes sense with the movie (Example: Consolas would be great for a movie like Primer or Tron) and use free style subtitles - like the ones in classic adventure games. </p>

<p>If you're not aware about these games, check out Full Throttle Opening on youtube.</p>

<p>Then again, here's some ideas about people talking simultaneously:</p>

<p>If they are from opposite sexes you can use different colors for each character. 
One character's lines could be on the right side of the screen while the other is on the left. 
You can even use different fonts (not recommended) </p>

<p>But, according to the usual pattern you should identify the characters who are speaking with brackets and simply show both lines at the same time. </p>

<pre><code>[John Doe] I love you Mary. 
[Mary Doe] GTFO, I hate you. 
</code></pre>

<p>But, as mentioned before, I <strong>strongly</strong> recommend creating a unique style for your movie, specially since it's only a few lines. </p>
