just a couple of things about the tv idea: i see in the fcc forum people were saying about the noise and disturbance this may cause, but on the other hand wanting more announcments to be done i.e welcome aboard, travel info, thanks for traveling. i have no problem with this except it cant be done with a doo train unless you have some kind of pids/pis fitted to the train that can recieve the infomation from a wireless device, other wise it would mean the driver doing it, how would he recieve the infomation via text on his work phone ( big no no just look at the crash in LA caused by the driver txting), via the cab radio ( as the csr (cab secure radio) only let one call at a time be made in a certain area, this has massive implications if their were an emergency and the line was blocked because of a tube update), i personally think it will be a good idea to have these fitted, but maybe only sound when there is a travel update coming through/ safety announcments/next station, and to remain quiet when the adverts/commercial info is going.
just my two pence worth.