This guy is an attorney in Las Vegas who has been contacted, he claims, by many of the bikers arrested in the Waco shootout. Easyriders magazine found him credible enough to pass the clip, given what they're hearing from their own connections.
The way he tells the story, most of the bikers inside were there for a meeting of a community of non-outlaw clubs considering bills before the state assembly that deal with motorcycle issues. The Scimitars and Cossacks showed up uninvited to this meeting. A handful of Bandidos showed up later, and the Cossacks/Scimitars decided to press their substantial numerical advantage to force the Bandidos to a loss of face. This escalated, so that one Bandido was shot, and one-two more shots were fired without issue.
Then the police, who had their SWAT team on site, opened fire into the crowd with rifles. He estimates they killed all 9 dead, and injured 26 of the 27. Then they arrested everyone, and got a justice of the peace rather than a proper judge to slap that $1 million dollar bond on everyone.
Now of course this is in no way official, and is just the word of people arrested at the time. The police have all the forensics and video, mostly unreleased to the public so far. Perhaps a FOIA request from a Texas media outlet will generate more information. Perhaps the police will choose to release more. Presumably there are some official procedures of inquiry in process as well.
We'll just have to see how the facts shake out in time.