On Thursday of last week, a number of users subscribed to Google Reader and who browse with Internet Explorer 7 were encountering problems where Google Reader would load a blank page. The issue was brought to a Google Groups discussion.
After a few hours, Mihai Parparita of the Google Reader Engineering team wrote to say that the problem was fixed and was related to posts that had embedded video.
We have now released a fix for the problem (you're right that it affected posts with embedded video). A reload of Reader should pick up the fix.
There have been other outages in the past, such as the one where feeds were not being refreshed and half Google Reader's users were not able to access feeds. Let's hope this is the last of it. :)
Forum discussion at Google Groups.