Why can I no longer watch music videos in full screen mode via a playlist in the music app since upgrading to ios7?

Question

Since upgrading to ios7 my iPhone 4S no longer allows me to watch music videos in full screen mode when I select the clips via a playlist from the music app.
It's now more necessary than before to use the music app rather than the video app to select music videos to play.  That's because the video app doesn't list music videos by artist any more. And also because the fast forward and rewind buttons on headphones remote no longer work on videos.
How do I watch full screen videos when rotating my iphone now shows my music library rather than showing the video itself?

Answer 1

I do not think it is a problem to play videos in the full screen mode using the video app.  It should work just fine, it does work ok for me  on iphone 5.  The original question was to play music videos in the music app.  Music videos and videos are two different things - I am not sure why but they are.
The problem here is that the music app supports lists and the video app does not.  I just looked at the ios7 video app and while my few test videos are shown in it, the lists they were in (in iTunes) are nowhere to be found.  There is no lists in the video app - period - which is as it was before. 
The video app plays videos and music videos in the full screen mode no problem but if you have a few hundreds or more of such videos you will have hard time finding the one you want to play.  There is simply no way to categorize or group videos.  The old good folders/directories are, I guess, too simple for Apple.  It is just too bad that for years on end the world's leader in S/W development did not offer anything to categorize videos.
You have lists, albums, etc., for music, you have albums for pictures but you have absolutely nothing for videos.  And this is and has been the Apple's state-of-the art solution for this problem - simply insist that the problem does not exist.  Actually it is getting worse.  Not only there is nothing to categorize or group videos but now the only way it could be done (by marking videos as music videos and using the music app) results in a mini playback area. 
Soon this OS will be able to cook dinner for your but grouping videos... no way.
What is happening here???