Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
modification : this agreement may not be modified except by a revised terms of service posted by vimeo on the vimeo site or a written amendment signed by an authorized representative of vimeo . 

```
. OPTIONS: ["None", "Unilateral change", "Limitation of liability", "Jurisdiction", "Content removal", "Arbitration", "Unilateral termination", "Choice of law", "Contract by using"].