...is there a way (next year or sometime in the future) to be able to show all contest entries at some point during the con? They do this at Sakura Con, and it's always something I look forward to.
Generally (and this year also) I work in some of the 'almost made it' AMVs into the Pre-show or the Show, and if there are open slots or extra time left over, sometimes an editor will be present and ask 'can you run my entry while we have everyone here, so I can observe an audience reaction?' and I have done that too.
The editors can see if the audience reacts to the scenes the way they expected, or how many seconds it takes them to 'get' a scene and react, and then they can sometimes re-tune entries to re-submit them into future contests.
For example if you setup a double-whammy and the audience noise hasn't yet settled down from the first gag, then they won't hear the audio which might be needed to understand the second hit - which becomes a 'dud' because nobody got to hear the set-up for it.
There was one time in which I had scheduled a dedicated block to show runner-up entries, but these are audience-driven events, and it turned out that the audience soon became interested in watching more entertaining works, such as winners and higher-order runner-ups from previous contests, and so we switched the content to follow the crowd.
Recently we threw one of the runner ups onto the screen and it was one of the almost-max duration slow-pokes, all 4min and twenty-something seconds of it, and from what I could tell the audience pretty much sat there until it went away.* (This is what the judges' panel does FOR you - so you don't HAVE to!) So, when I show runner-ups, rather than committing to showing the entire block, I try to steer toward the higher-scoring runner-ups or works with lesser-known anime or unusual styles.
(*if there was a set of distantly-seated, highly-energized viewers in the audience whom I did not detect, then I offer my apologies.)