@gaz - I don't know if this is the same in Scotland, but in England and Wales whilst the task mostly falls upon the council, and it is likely not a policing priority, to drive in a bus lane whilst it's operational is a road traffic offence. Granted there may be an exclusion for emergency vehicles, but that does not stop the police car from setting a precedent/ if there is no immediate need for the car to be there why use special privileges, why not behave as you expect others to act?
AFAIK, it is the responsibility of the Police in Scotland to enforce bus lane infringements, or in the case of cameras detecting offences, the council. Having said that, I worked in the Inverclyde district where there is not a bus lane to be seen. There is always the "fail to obey a traffic sign" to fall back on; that covers pretty much everything. Re your point about there being no immediate need to be in the bus lane, how do we know this from the clip? Not every call is as clear cut as being either a blues and twos emergency, or a "sit in traffic and wait" response. There are loads of incidents where you want to get there quickly, but don't merit an emergency response.
I'm in full agreement that the cyclist is silly, but what baffles me more is the unquestioning obedience towards the police displayed in this thread. When in the video it's quite clear that their actions towards him are motivated more by him challenging them, than any offences he may have committed.
I'd like to know if those who don't believe that he should be able to question the police's actions directly, can envisage any form of action by the police which should be directly challenged? Essentially at which point do you intervene, or should you always leave it for an organisation to question afterwards?
I would suggest it is always a bad idea to intervene at the scene. You won't know the background to a specific incident and by sticking your oar in, you are leaving yourself open to being arrested for obstructing the Police in the execution of their duties (if it was to escalate that far). The proper way is to complain after the event, at a Police office.
In this particular case, when I was a serving Officer I most certainly would have challenged the cyclist. I would have gone about it a different way, i.e. I would have explained the fact that Police vehicles are allowed in bus lanes, and that at that particular time I was heading to deal with another incident and therefore didn't have time to book the other cars using the bus lane.
I would have REQUIRED him to provide me with his name and address on the grounds that he was a potential witness to an offence (was he not complaining about vehicles in a bus lane at some point?). Section 1 of the Criminal Justice (Scotland) Act 1980 used to provide Police with that power (and maybe still does). Having required his name and address there is no way I would then let him cycle away! I would have arrested him at that point. As a Police Officer you MUST NOT require someone to do something and then not follow it through, that is rule #1. If you do, then you just look silly like the guys on this clip.