I don't want to judge who is right and who is wrong in this. Probably everyone involved could have prevented the final outcome of this.
But I think you are wrong with your assumption about the eviction and some other stuff.
Listening to the Audio before the whole incident it is basically said that VC needs to leave the venue immediately, and that they do not want to argue this any further with VC and he can call whoever he wants after he leaves the venue if he thinks he is treated unfair. Even if he had a valid reason to enter or a ticket at that point you have to follow the orders of the people tasked with security or official functions at the venue.
You can sue them afterwards for your ticket price or make a giant fuzz on social media, but if you get asked to leave by someone with authority in the venue, you leave. It's a very simple principle. In the end a guy in the recording even tells someone else to call the police in German. Everyone seems to be calm but fed up with VC, still there was no reason for violence at this point in any form or shape.
So something happened between the recording and the video.
And from the blog entry and the following video it's believeable that VC wanted to leave the venue. Knowing the venue from exhibitions and conferences, it is as he describes, he tried to get out and not back in when he was grabbed by multiple people who he claimed were staff / security. He was heading straight for the door not screaming or throwing punches or anything.
Now this is where it gets a bit complicated.
If you refuse to leave a venue, a professional security company will always try to isolate you and then tell you that the police is on it's way and because you are trespassing now you can't leave any longer. We make it clear to you that you are no longer able to leave because you broke the law and we are pressing charges as soon as the police arrives and that gives us the right to keep you in place and hand you over to the police.
If you do not cooperate we can use the least amount of force that is necessary to keep you in place until the police arrives. You can still phone, film or record as much as you like and nobody will touch you as long as you don't try to run or do anything stupid like grab a knife from your pocket or anything that could harm us. It's also not up to staff to steal your phone or prevent the recording.
So the question is if VC was told that police is on the way and then tried to leave the venue. Which would justify the use of force to keep him there, but not in the way it was applied which was very excessive and unprofessional.
That said, here are just two other pointers that this was not a professional security company or most likely not even people with proper certification.
- Proper security doesn't pull up hoodies and put on gloves to team on someone when they are aware that someone is filming. This looks more like Dodgers Antifa friends. Look at the video in the blog post and then at https://b3b76917eedfeb0c4dd3-af59c7b3e9e42ed4215be8c7a95ca95... and you'll see what I mean. Security doesn't dress this way, especially at any professional event. Who wants to look like a bunch of thugs representing a proper business?
- Proper security doesn't try to snatch an eyewitness phone and then tells them he can do shit "because you can't find me on the internet" after showing her crew sweater and face into camera. What a dumb bitch (personal opinion).
No matter how you look at it. VC has the right to stay unharmed and treated properly even if he broke the law and they are pressing charges. Germany is not an open PVP Zone like Texas. And it's CCCs responsibility to guarantee that people under their protection stay unharmed. Especially by their own staff or external service providers.