I don't know about trails but somebody rode their bike down Balches Slide at Fairy Cave Quarry, that's a good rock slab (I don't condone this by the way).
That vid totally blows away the one in the OP. I remember seeing something in a really old MBUK mag of someone riding down a massive (~60 foot) ~45 degree slope in scotland that looked pretty mental but I can't remember where it was.
Fri Night Vid Finding Focus - Life Behind The Lens of a Climbing Photographer
This week's Friday Night Video is a portrait of a prolific climbing photographer from Wedge Climbing. Sam Pratt is well known in both the outdoor and competition scene but if you haven't heard of him, you've likely seen...