Our business uses Vimeo because we get a discounted rate on acami CDN via their bulk purchasing power. YouTube is free but that comes with a lot of headaches. For example not being able to hide the recommended videos at the end of a video, which annoyed our clients in the past when we did use YouTube. YouTube also needs to be public to be embeddable, which also created issues for us. However this announcement has me terrified and literally scrambling for a backup plan.

Vimeo you manage your brand and presentation. YouTube you have little control over where or how your video is presented. Vimeo also provides VOD for some large brands and media companies.