I'm not usually one to claim that video snippets are worth much of anything, but I don't think either person came off particularly well - the aikido guy seemed to throw "cheap" strikes that weren't particularly effective, the bjj guy (a white belt) kept trying to pull guard until the end *grumbles*, when his o soto gari was successful, but he got rolled and the aikido guy held him in kesa gatame.
I'm not sure if they had agreed to a ruleset (the comments weren't clear), or if the bjj guy assumed the aikido guy would spar according to jits rules (which is what I would assume if I was crashing their class). The bjj guy claimed that the aikido guy was going for nut shots, eye gouges, etc., which I think is pretty much dirty pool unless you're attacked or the ruleset agrees upon is really "anything goes".
Thing is, everyone's got a belief system, everyone's got a plan (until they get hit) and most people already know everything anyway, so they don't usually take advantage of trying to learn something new. But if I'm a guest at someone else's class, I play by their "rules" - simple good manners.
Today's aikido guy that talks down on learning grappling will be tomorrow's bjj student trying to tell us how to "fix" aikido. Today's bjj guy that doesn't learn takedowns (or train how to "not" get taken down - yes - they are out there) will be tomorrow's wrestler/judoka that wants to "fix" bjj. Today's wrestler/judoka that doesn't think strikes are useful will be tomorrow's mma player looking to point out where each art has holes. Tomorrow's mma player might not ever become really "great" at any aspect of their game, but might focus on "lay and prey" stuff that works great in a cage, but not so much in the real world.
Basically, today's guy that already "knows the answer", will be tomorrow's guy telling the person using his "today answer" why he is wrong tomorrow, without realizing that even tomorrow, there might still be more he doesn't get.
In other words, never assume you have the answers, get out there and train with people that know things you don't. Keep researching, keep improving and don't be an asshole if you can help it.
Note to self: Periodically remind myself to take my own advice . . .