G Drive 1Tb not able to repair

I have a very similar problem with my G-Tech Drive Q 1Tb as earlier in this forum was mentioned. Bought it March30, 2009 on recommendation of Apple Genius (?!). Drive is connected to iMac Intel. At first drive did work flawless. I think it was June/July that there were issues like unbelievable long time for Time Machine to find the differences to have an incremental backup. To the extent that I disengaged TIme Machine. Only so now and then I instruct Time Machine to backup. Backups were performed but drive was 'hanging' and could not be removed in accordance with dismounting procedure. Only way out was to power off the drive. Yes you get the message that it was removed improperly. Now things get worse. After I installed Snow Leopard and running disk utilities to find out if disk utilities could help to repair the drive it came back with a message that it was impossible to repair the drive! As I had video material on the drive I started immediately to copy video's. This however is partial succesful. After 4-5 video's it started to copy but did become stuck. Nothing helped and final resolution again was to power off the driver. Today's status is that drive mounts so now and than, you even can see the content, but when trying to copy it hangs.
Please help me to see if I can recover my video's before reformatting or other disastrous measures.Regards.