[SOLVED] After upgrade, YouTube suddenly disappeared

I just upgraded to WordPress 3.01, as well as my Atahualpa-theme, and suddenly all of my embedded YouTube-videos have disappeared from both my posts and pages.

For example here:

http://www.peterdyreborg.dk/?page_id=51

I think I once read that it is possible to make a change somehow in the CSS and that this will fix the bug, but I cannot find the advice anywhere on this forum or via Google.

Does anyone know how to fix the problem and get the videos back?

All the best

/pdm