The error messages indicate significant incompatibility of your 5.1.1 libraries with what is *now* "testing" or "unstable" in the repositories.
Invoking apt-get -f install (as it suggests) *might* work OK but it would be a pretty brutal upgrade step and might leave you with problems

I suggest that you (backing it up first) replace your /etc/apt/sources.list file with the following which I use with 5.1.1 (I've left in the 'cruft' which you can remove if you like).
[Edited line deb ... download.videolan.org/pub/videolan/debian sid main 14:07 hrs BST]
Code:
 # deb http://ftp.uk.debian.org/debian/ etch main

deb http://ftp.uk.debian.org/debian/ etch main non-free contrib
#deb-src http://ftp.uk.debian.org/debian/ etch main non-free contrib

deb http://security.debian.org/ etch/updates main contrib non-free
#deb-src http://security.debian.org/ etch/updates main contrib non-free

# VLC Player and libdvdcss
#deb http://download.videolan.org/pub/videolan/debian sarge main
deb http://download.videolan.org/pub/videolan/debian sid main

# w32codecs
#deb http://www.debian-multimedia.org lenny main
deb http://www.debian-multimedia.org etch main

# cinelerra
deb http://www.kiberpipa.org/~minmax/cinelerra/builds/sid/ ./
If you are in the us you can replace uk by us to get your nearest mirror, or whatever is your appropriate country code.

Then invoke successively
Code:
apt-get update
apt-get install grip
and good luck