I created an event via the Web site which contained an embedded video in the description. I then updated the description via the API. The API stripped out the embedded video content that the Web site left in.
From my logs, here is the original content I received via the API (note my log has converted unprintable characters into 0xXX format), and note the embedded video is there (soon after "CLICKING HERE"):
From my logs, here is the content I updated using the API (note I am adding some content at the end, everything else is the same):
From my logs, immediately after the above update, I do another "get" to check for this bug and here is what I get back (notice the removed embedded video soon after "CLICKING HERE"):