The whole idea of buying dvd's is to watch them when you want ,not when tv channels decide to air one ,along with edits ,logos,adverts,voiceovers and no Dolby Digital sound (unless you pay for Sky Movies).
Have not seen any extra features on tv.
With movies going down by 50% within a few months its certainly good value unless you want to wait a further 18 months-2 years for it to show up on tv.
I have not watched a mainstream film on network tv for 20 years.