Have u tried different browsers? Safari does this sometimes but so do other browsers... but ye, try 2 - 3 other ones (mozilla, chrome, opera)
if it didnt work make sure you have cookie & javascript ENABLED on your browser.
And if this sht didnt work try ddeleting your cache/broswer data. tools > clear browser data (in the dialog that appears just check what u want.) > click clear browsing data
and if it still doesent work check if you have latest flash player installed
^NOW if none of that worked theres a chance its Vimeo's own bug, they had one awhile ago which would display the error message but they fixed it back then. but i doubt that.
u better give me some karma for this because of you, i now have to start watching Iron Man 3 15 minutes later than i planned to. have a nice day/night whever you live.