A quick recap on a much-updated post:
Vimeo proudly claims to be ad-free but this isn't true. If you challenge them they qualify it by saying "there are no ads on our platform." Most people would assume "our platform" means Vimeo (just as Facebook and YouTube are commonly called platforms) but their own in-house definition of "platform" is "the video player." Below the player, in the region where comments and older videos are located, they serve annoying banner display ads. They claim that is only on "some" pages but that's not true either -- as of this writing I am seeing them on all my pages.
The "Plus" plan ($7 a month) serves ads but you can get rid of them by paying $20 a month for a "Pro" plan.
In true corporate style, if you point these inaccuracies out, the customer support staff tries to snow you by saying that "as a Plus member you will never see ads." Good to know!