A man, understood to be Ron Davies, was filmed placing rocks and logs on Caerphilly Mountain.
He denies intending to hurt anyone with the obstructions, which follows a row over how mountain bikers use the area.
Natural Resources Wales (NRW), which owns the land, has encouraged both sides to meet to resolve the issue.
Ian Clarke from Van Road Mountain Bikers said: "I can appreciate that maybe some people don't agree with the way we use the woods, but I think if you're putting other people in danger, that's a problem for us."
It is not against the rules for mountain bikers to ride on these unofficial trails, providing they do not cause any damage to wildlife or the environment.
NRW recently cleared mounds and other structures built without permission by bikers amid safety and conservation fears.
Signs advising them of how to go through official channels were torn down and defaced.
Mr Davies and another man, who also lives locally, were filmed by cameras placed near one of these unofficial trails.
Neither wanted to be interviewed by BBC Wales, but both denied intending to deliberately injure anyone and said they could not remember which trail the video showed.
Footage has emerged which appears to show a former secretary of state for Wales helping to block an unofficial mountain bike trail.