The first thing to notice is the M5 jumps a bit and is ahead at the start. The E63 makes up the difference though which is impressive and although this is a fairly short run (not a 1/2 mile) and the cars do not stretch their legs fully it shows tune only versus tune only is going to be close and decided by supporting modifications and the quality of the tune.
The ETG (ECU Tuning Group) tune does not appear to be providing the F10 M5 650+ whp with bolt ons. ETG does not really provide dyno's as support and their tuning quality is questionable based on their history but an M5 with more power should win especially considering its transmission advantage. The Renntech tune shows very well on the E63 considering it makes up ground versus what is supposed to be the more powerful car.
This M5 vs E63 battle is getting into full swing and will of course go back and forth for some time to come.