To delete video from your iPod Touch without connecting to PC or Mac
Do the following:
Go to your videos and look for the movie that you want to delete, after that on movie line just move your finger to the left . It should show you delete button, press on delete button and that's it.
If you don't want to delete the movie and just test this ipod touch trick, move your finger to the right and delete button will go away.
Once you connect the iPod Touch back to your pc the move will re-sync.
Delete movie before you reconnect your iPod Touch to the pc or mac.