A new version 0.1.1 was just uploaded to extra repository which addressed video restriction or flash missing error problem due I've overlooked some of the code which was finally fixed now, and also fixed several bugs which was reported previously including canceling download and early stop video before it load crash .
Big thanks to kpyork for reporting a very thorough bug reports.
In regards to my problem browsing "Downloaded", when it was pointed to .../.videos/ (containing non-YouTube videos)....
I did some research and found the cause of the "Restricted Access" error.
You scan files for.. "MP4 v2" files encoded with "H.264/MPEG-4 AVC & AAC", and ignore all other files.
The problem file is "MP4 v1" files encoded with "H.264/MPEG-4 AVC & AAC"!
In regards to my problem browsing "Downloaded", when it was pointed to .../.videos/ (containing non-YouTube videos)....
NVideo won't be able to display non-youtube video by design. If you pay attention to all downloaded video files name by NVideo, it included a youtube videoid in order to retreive meta information from youtube server. If you clicked the downloaded tab, you would see all downloaded videos display all the information just like they are on the youtube server. That was because it scanned all the videos file names in the downloaded folder for videoid and retreive meta info based on that videoid. So try to have a dedicated folder for all downloaded youtube videos would be ideal. Future version would include a more sophisticated way to handle local videos.