To answer the original questions, my LCC airline has noticed very little change as our procedures were already in place to comply with the new legislation. As shown in the video, it is the airport who is responsible for providing the majority of the assistance required, the airline only being responsible for passengers on board (and disabled passengers need to be largely self-reliant or accompanied with a carer if not). If you require assistance, be sure to book it as early as possible (at LEAST 48 hours before flying) and arrive at the airport well in advance (at LEAST 2 hours) before flying to avoid problems. Sometimes we do need to board disabled passengers last if they are not at the airport in time for boarding first (or if the airport is in a remote corner of the EU and lacks the efficiency of the Belgian airport shown in the video).
To answer a question about costs, airlines themselves have very little additional costs, as it is the airport which provides the majority of the services. (The airport then charges the airlines for all the facilities and services it provides which is why the 'fee' portion of a ticket varies from airport to airport).
To contribute to the discussion on other forms of transportation, I read some research in Australia that showed it was cheaper to continue providing vouchers for taxis than converting buses to accommodate wheelchairs, and in general this was the preferred option by wheelchair uses at the time as it was a door to door solution (no cracked footpaths to negotiate and waiting for buses). However, the buses have now all been updated and the taxi vouchers no longer exist. I'm sorry though I can't find the original source as it was about 10 years ago.