I can't wholeheartedly recommend these films, but they do have something to them - maybe just the fact that they're both the work of obsessives, now empowered by (relatively) cheap video cameras and editing programs:
Six Degrees of Helter Skelter
is basically a fan film in that it was put together by a man (Mike Dorsey) obsessed with Manson lore, and a whole pile of other things besides. He gets right into the minutia of the story, every goddamn small detail, and while it's not gripping viewing it is somewhat entertaining to watch him wander around the various sites associated with the Family, burbling the knowledge he's accumulated through the years, getting excited over finding small pieces of Spahn Ranch relics. I swear that it barely registers with Dorsey that actual people died - to him, the whole thing is just one big scrapbook he gets to show off to people.
There were enthusiastic amateurs in charge of
Resurrect Dead: The Mystery of the Toynbee Tiles
as well, nerds on their own little Scooby Doo adventure, but the mystery is at least fascinating. They're trying to track down the source of the Toynbee Tiles, those strange linoleum plates that someone has been inserting in various streets in the US (and one in Chile, as well) for decades now. It drags a little at times, but there's always something worthwhile in watching someone else's mania.