A fairly standard and entertaining documentary is Jack the Ripper: Phantom of Death. Despite the somewhat idiotic title, it features Martin Fido, Melvin Harris, Donald Rumbelow, Stewart Evans, etc. which makes it rather interesting to watch. Several copies of rather poor quality can be found on youtube; this one is not too bad, and is split up into four parts, each about 12 or 15 minutes in length. Have fun with it.
Barlow and Watt: Jack the Ripper is a part-fictionalised, part-historical serial from the early 1970s, but has some excellent performances and good attention to period detail. A lot of the contemporary characters' words come from newspaper/inquest reports etc. Well worth watching.