I posted about a week ago that there was a problem with the "Earn free farm cash" tab i.e. that a screen briefly appeared for a couple of seconds, attempted to load , then disappeared again. Then the tab and the video ads disappeared altogether for a few days.
Today the tab is back, but with exactly the same problem.
Moderators, I don't know how much money companies are paying to have their advertisements screened on FV, but I would imagine that they're not getting their money's worth if the adverts won't even load. Have you made Zynga aware of this ongoing problem?