Use Media Youtube with File Field Type
In your feed importer mapping, change the Source to Watch page.  It seems Video URL is broken.

I have it working right now with the following modules:


Feeds (feeds)  7.x-2.0-alpha7
Feeds: YouTube (feeds_youtube)  7.x-2.0-beta1+7-dev
Media Feeds (media_feeds)  7.x-2.0-alpha1+9-dev
Media (media)  7.x-1.2
Media Internet Sources (media_internet)  7.x-1.2
Media: YouTube (media_youtube)  7.x-2.0-rc1


All dev versions were as of today (Dec. 1, 2012).  And for anyone that's trying, I found Embedded Media Field (emfield) to not work with Feeds at all.

Using the File field type (the widget type doesn't matter for feeds imports), set the display to Rendered file.