user22561: The folliwng should basically have an image appear on frame 438, and then the same image move to a different position on frame 339, then basically disappear for the rest of the video. 
ffmpeg -i C:\src\assets\video\base.mp4 -r 25 -i C:\card.png -y \
    -filter_complex [1:v]setpts=PTS-STARTPTS+(1/TB)[1v]; \
    [0:v][1v]overlay=x=0:y=0:enable='between(t,438/25,439/25)'[1v]; \
    [0:v][1v]overlay=x=300:y=300:enable='between(t,439/25,440/25)'[2v]; \
    [1v][2v]concat=n=2:v=1:a=0[out] -map [out] -map 0:a -ss 17 C:\temp\j7kthb0v\composit.mp4

I can't seem to get the actual command correct or output anything that resembles what I need. 
I know I'm close, I can get one frame overlayed, but I can't get more than that. 

user1871: Use
ffmpeg -i C:\src\assets\video\base.mp4 -i C:\card.png -y \
       -filter_complex "[0:v][1:v]overlay=x='if(eq(n,439),300,0)':y='if(eq(n,439),300,0)':enable='eq(n,438)+eq(n,439)'[out]" \
       -map [out] -map 0:a -ss 17 C:\temp\j7kthb0v\composit.mp4

You may need to escape the commas in filters depending on your shell i.e. n,438 -> n\,438

22561: <p>The folliwng <em>should</em> basically have an image appear on frame 438, and then the same image move to a different position on frame 339, then basically disappear for the rest of the video. </p>

<pre><code>ffmpeg -i C:\src\assets\video\base.mp4 -r 25 -i C:\card.png -y \
    -filter_complex [1:v]setpts=PTS-STARTPTS+(1/TB)[1v]; \
    [0:v][1v]overlay=x=0:y=0:enable='between(t,438/25,439/25)'[1v]; \
    [0:v][1v]overlay=x=300:y=300:enable='between(t,439/25,440/25)'[2v]; \
    [1v][2v]concat=n=2:v=1:a=0[out] -map [out] -map 0:a -ss 17 C:\temp\j7kthb0v\composit.mp4
</code></pre>

<p>I can't seem to get the actual command correct or output anything that resembles what I need. </p>

<p>I know I'm close, I can get one frame overlayed, but I can't get more than that. </p>
 1871: <p>Use</p>

<pre><code>ffmpeg -i C:\src\assets\video\base.mp4 -i C:\card.png -y \
       -filter_complex "[0:v][1:v]overlay=x='if(eq(n,439),300,0)':y='if(eq(n,439),300,0)':enable='eq(n,438)+eq(n,439)'[out]" \
       -map [out] -map 0:a -ss 17 C:\temp\j7kthb0v\composit.mp4
</code></pre>

<p>You may need to escape the commas in filters depending on your shell i.e. <code>n,438</code> -> <code>n\,438</code></p>
