Here’s what I experienced:
1) Went to http://vimeo.com/channels/hd/41499247 within Kylo, video area was large white box.
2) Tried same URL in Firefox (version 13, latest), got same large white box
3) Started googling “firefox vimeo”, found a few complaints regarding similar experiences…
4) Went to http://vimeo.com in Kylo and Firefox. Same large white box in place of video - so not related to specific video you posted, but rather all of vimeo… strange.
5) More googling…
6) Found this: http://support.mozilla.org/en-US/questions/923633, see a buried mention of RealPlayer
7) Remembered I had installed RealPlayer to test some other issue you were complaining about…
8) Uninstalled RealPlayer
9) All vimeo videos now play perfectly well in Firefox and Kylo.