I graded a best bet thread for many months, and I just used sbrodds.com, whenever someone posted a line and the site they bet it, you can verify what the line was at the time they bet it.
also was the "judge" on a $1k prop bet on whether or not someone would be up or down units after 150 bets, used the same site.
if they're using 5d, that's pretty simple to check. hell there are people here that have spreadsheets with scraped data of every line movement from open to close...
if you think I'm gonna watch this and not point out if someone is posting better lines than were available at the time of their post, you're really wrong.
you should also make a rule that no one is allowed to edit their posts when posting a pick... in the 30 minutes you can edit, a line can move a lot. if someone were to post a game with -144 odds and it moved down to say -132, there's nothing to stop them from editing in the new price.
I guess mods can see edits though right?