Any sifu please help me here

I have taken a video which is 1GB inside my ipad, and when i open it, suddenly it crashed and created fragmentation. Now my others is stucked at 3GB while previously it is 1.8GB only! I lag twice so i assumed there were 2 framentation of the video there. How can i delete it ?

Or the worst case how can i restore a jb iPad ?

And here one method to reduce it, but I don't know whether it can be 100% work for all of ipad device.

1. opne /var/mobile/Media and find "itunes_control", if there is "itunes_control2", delete it. And then check "Others". If nothing happened, go to next one.

2. find "Music" in "itunes_control", and delete all of folders in "Music" and sync your music and movie again.
Note: please resync your music and movie

3. or you can try icleaner to remove junk data

or restore

Use ifunbox to manually delete files