There are some idiot bikers, and because bikes are so quick compared to cars they do tend to make a nuisance of themselves, but they are the minority as far as I can tell (I ride a bike and drive a car regularly)
On a dual carriageway/motorway, I won't ever immediately undertake someone, however if they've passed several large enough gaps for me to see that they cba to move out of my way, then whether I'm in the car or on the bike I will undertake, if in your instance the biker undertook you almost immediately after coming up to you then that's pure recklessness on the bikers part.
Same with the filtering, if it's safe to do so (by safe I mean I can get through without knocking anyone's mirrors, or worse) then I'll do it, I won't do it if it requires either car to move out of the way though, again that's just silly.
To repeat, there are bad bikers, but as an added point I'm much more concerned about the bad car drivers, yes there are more of them, and imo there are probably a higher percentage of them (at least until the summer month's when the true fair-weather riders come out to try to kill themselves). If I'm in the car a bad driver, or bad rider, will simply cause an accident, 99% of the time that will be simply an annoyance. However if I'm on the bike that same bad driver can pull into the side of me on a roundabout, breaking my leg and giving me a nice 2 week spell in hospital, 3 months off work, 6 months till I can walk without a limp and for good measure I'll never be able to run any distance and my knee's will ache/be painful for the rest of my life.
Bad bikers are fine imo