Embedded videos crashing my page

Hi,
everytime I embed a video (e.g. youtube or vimeo) on my blog, I get problems with IE6 + IE7. The site doesn’t load completely and an error message pops up. After pressing the “ok” button, I get an empty site.

With Firefox everything works properly.

Any ideas?

https://www.konniwinkler.de for my blog and https://www.konniwinkler.de/page/12/ for an example of the error. On this page a video is embedded.