First of all yo need thier land line connection for using Internet, landline which is pathetic because of the heavy minimum bell.About broadband you even never get the total 512kbps bandwidth.Most time I have disconnection problems, thete are other broadband like asianet which are far better than ever bsnl will be.For downloading and watching videos and movies.
I recommend asianet broadband.Which gives 1mpbs bandwidth at the same rate as bsnl.