Not exactly a problem that I am having, except that it does kind of affect me...
When I embed a video from YouTube to the forums, the site works out the appropriate width for the frame that it's put in so that it fits nicely into the width of the forum post. So far, so excellent!
However - when the same video is embedded into a blog by a friendly RSPB person, the video frame is NOT resized. So - it's too wide, it overflows the width of the post, and the right hand side of the video isn't visible.