1. I am thinking about it. Not a problem to implement. I just don't understand why? You can start playing music in music hub as well as delete it . No additional features could be implemented in PFM for music as we (developers) has no direct access to music files.
2. About video files. There is no way to SEND file to another application. Only ask System to open file with supported extension. Yxplayer should implement this feature to accept video files and subtitle files. Of course we have a limitation here. Application cannot overwrite system reserved extensions like .mp4 and so on. So Yxplayer must register its own extension, for example .yxp. You, as user, rename files by adding .yxp to the name of file (myvideo.mp4 to myvideo.mp4.ypx) and open it from PFM.
Pocket File Manager registered special extension .cfs. So any application can open file in PFM by adding this extension to the file name.
.cfs is the official PFM extension, so yes, it will work with browser too.
To avoid questions why CFS, not PFM.
I was though that it would be good to create universal extension (Common File extenSion) so any applications can exchange files. As windows phone prevents us from being good userswe can do something to make our live better. For example any app can register to cfs and later wait for files.
For example one app receive only .doc files. So other app can rename "example.doc" to "example.doc.cfs" and ask phone to open it, other app when receive such file will remove .cfs and check for original extension and if it suits this app, save it or do whatever its want .
But unfortunately I did not found developers who interested in this idea.
Just popping up this thread and want to inform you that new version currently in development process.
And now you will get long awaited features:
+ Access to video files
+ Access to high resolution photos on Lumia's 1020/1520
+ Full access to media library. That is, you can now delete images and videos from media library.
+ Could be possible, but cannot guarantee to be in next release. Full access to SD Card.