Probably the best way to defend yourself against this is masking all your personal information and not showing where you are. It at least shortens the list of people who could have made the 911 call to people who actually know where you live, i.e. people you know in real life. It probably also helps not to use a webcam, because the people who get a kick out of this probably get more of a kick out of it because they can see it happening on the stream and record it.
As far as police brutality goes; it's kind of a fine line. If a guy is surrendering himself so obviously as was the case in the video, there is no need to step on his head once you have guns pointed at him and he's pinned to the ground and surrounded by multiple officers. On the other hand, those SWAT-officers probably have quite some adrenaline rushing through their veins because they are looking for someone who is armed and reportedly firing, so it is sort of understandable that they just instinctively try to dominate their targets for their and others' safety. You can clearly see that their aggression and adrenaline lower as they start realising that there is no threat. However, officers receive training to deal with these situations and they should know exactly how much force to use to be safe without discomforting potentially innocent civilians. I also can't imagine that they haven't encountered someone laughing when they get raided before, because a reaction of utter disbelief is probably quite common.
The "What are you laughing at?" is a typical tense response fuelled by adrenaline, it's more of a challenge than it is an actual request for information. It sounds like Kootra realised what was happening and why it was happening before they even got into the room... I would have chuckled too at such a display if I knew it was all because of some bored/spiteful kid on the Internet reporting a fake shooting incident.