It's an odd mix of rave hyperbole (how he "slayed the critics" and "packed in the audiences," which has much truth to it, though ignores that some of his successes were more modest than this suggests. Blitz!, for instance, had a solid run, a bit over a year, but had mixed reviews and was so expensive it lost money. And his last two shows were disasters) – but it also deals openly with his dark side. As does Bart himself. In fact, the film's current interviews with him are among the most interesting parts of the documentary, where he seems far more at peace with himself and reasonably open, after having long-since had to sell off the rights to Oliver! because of heavy drug use and rampant spending.
(Side note: the documentary includes footage and discussion of a major West End revival of then-current 1994 revival of Oliver! which was produced by Cameron Mackintosh, who owned the rights at that time -- and in a lovely act of generosity, gave some of the rights back to Bart. The film makes brief mention of this, but doesn't clearly explain what, in fact, Mackintosh did.)
The documentary loses audio around 8-minute for about 20 seconds. To clarify things, what you won't hear during that portion is that they're discussing his early work with pop star Cliff Richard.
One particular thing that viewers might find fun and worth noting. At 13:45 in the film, you'll see an interview with an actor named Barry Humphries, who appeared in a couple of Lionel Bart's shows including the original production of Oliver! as 'Mr. Sowerberry' the undertaker, the character who buys Oliver from the beadle Mr. Bumble. Humphries appears throughout the documentary, and has thoughtful comments. Though most people in the U.S. won't likely know him by his real name, he's actually very well-known. Humphries is far-better recognized by a character he played for decades -- Dame Edna.
A few other comments about the documentary. You'll see a few brief interviews with a grown-up Mark Lester, who starred as 'Oliver' in the film. Also, my fave Harry Secombe appears around the 26-minute mark. And at the 51 -minutes in, they discuss at length Bart's massive flop, Twang!, about Robin Hood, which readers may recall I wrote about here and here.
And here...is the documentary --