I don't know why a coax connection would damage the video, I think it was probably coincidence. Unless, possibly you connected it to the RF2 output of the digibox and the digibox had the 9 volt supply switched on - that mijght do it.
Are you in the UK? If you're not then I doubt you could get it to work properly anyway as the digibox outputs PAL I signals and most of Europe uses PAL B/G. The result would be video recorded but no sound.
Going back to the scart, I don't know why it didn't work. You should have connected the socket marked VCR on the Fortec to AU2 socket (the one that's NOT marked TV) on the Video. Then select AU2, Input 2, Line 2 (or something similar) as the source on the Video.
That should do it. I don't know the Fortec so can't be specific, I'm afraid.