If you tried transferring the videos and it quits on the same spot, its most likely there are glitches in it. Best way is to locate on the Tivo where it had stopped compared to the downloaded file, and see the glitches, pause just after. Resume download after paused point.
I doubt iTivo has that feature, but KMTTG does. I also suggest you upgrade to PyTivo.
Original S1 (Recycle Heaven)
Series 2 (PLS, sold)
TiVo HD (XL, PLS, "652")
Juliet Basic (4XL, PLS)
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!