The picture and video are consistent with an olecranon bursitis. Unless it became infected (septic olecranon bursitis), it shouldn't interfere with his fight. It is likely from trauma during his training. It may hurt a bit (or it could be entirely painless), but it shouldn't cause him to pull out of the fight or significantly impair his performance.
"Be of good comfort, Master Ridley, and play the man! We shall this day light such a candle, by God's grace, in England, as I trust shall never be put out."
--Hugh Latimer, October 16, 1555