The video caption below will tell you most of what you need to know, but here's a little more detail.
For reasons that remain unclear, these two gentlemen attempted to firebomb an English pub one night in May 2008. They devised a cunning plan in which Gentleman #1 would throw a brick through a window, and Gentleman #2 would then throw a Molotov cocktail through the previously broken window, whereupon both would flee.
It appears that Gentleman #2 carried out his part of the plan well enough, although he probably threw too soon. But Gentleman #1 failed spectacularly, both in his attempt to break the window to start with and then in the plan's flight phase (watch the upper-left corner):
The BBC has a zoomed-in version of the video that makes the debacle a little easier to see (brief commercial, though).
Oddly, the reports linked above both state that the police found "a petrol bomb that had failed to ignite," but it seems pretty clear to me it ignited just fine. (Maybe they had a second one they didn't get a chance to use.) But I think the videos make it pretty clear that Gentleman #1, later identified as a 28-year-old Londoner named Amir Ali, didn't succeed in smashing a hole in the window, and so the bomb thrown by his comrade bounced off the glass and back towards Ali. Somehow he avoided being set on fire himself, but his luck ran out during the ill-executed retreat from the scene.
Ali steadfastly denied being one of the men in the video, but Sussex police were able to link him to the incident after what they described as a lengthy investigation. Clue #1, though, was the fact that Ali had coincidentally shown up at a nearby clinic that same night with a head injury in a location that can be inferred from his later mugshot (right), and which roughly matches the impact zone shown on the tape.
Police theorized that Ali's vision had been partially blocked by the hoodie he was wearing in an attempt to conceal his face from security cameras.
Ali was later sentenced to eight years in jail for the attempted crime. His more elusive companion apparently has never been identified.