Since I do Hd Video editing and the iMac does not have an external eSata port I am willing to replace my dvd super drive with a hard drive if possible?
Yes, you can replace the SuperDrive with 2.5" disk. However, FireWire does ~80MB/s in real life which is sufficient even for video editing as most 2.5" mechanical HDs can't achieve speeds of 80MB/s so I would just get a FW800 external