One thing I have noticed about the "Other" category is it only appears to exist if you do not have "Sync with this iPad over WiFi" checked.
If I have mine off I have 9.5GB of Video and no 'Other'
If I check that box it reduces to 7.7GB of Video and 0.23GB of 'Other' , the Audio, Photos, Apps, Books etc. do not change. The Free amount changes from 15.7GB without it checked down to 14.4GB with it checked.
It seems there is something more than stated above about its contents as if it were as stated it would surely exist all the time and why does it only change the Video content?
Strange...