Here is the vid, it's Dex talking to JOJ on the phone about David's 120 pound curl. It was posted here back in 2011, but the vid doesn't work. Here is another link
http://www.ebaumsworld.com/video/watch/80630783/
he also stated in magazine he did a 130lb one arm tricep extension
but that video you posted i remember..... fund it funny because its not a bicep curl its a hammer curl...which is significantly easier...
heck Ive done that with 100's ...
hes also said he benched over 500.....
I dont have a problem with his claims.. but as i stated 120 hammer curl is miles away frm a 120 supinated bicep curl
on bfto 05 or 04 david nearly shit himself curling 70's and he wasnt a fully supinated curl.... he only baely got 3 reps
so... do the math