Hi!
A lot of users has been requesting this functionality for a long time, the plan is to enable embeding of flash videos (and forms/widgets/etc) though a placeholder system. This would enable the the site manager to decide how videos should be presented, while at the same time require very little of the user.
However, this functionality won't be available before version 0.6 of WYMeditor, so until 0.6 is released your patch could be a way to enable basic embed support for users who want it. I don't think it'll be included in the official release though, as it seam to break Firefox support.
Cheers!