Yes I have, but I don't trust either side. John makes a reasonably valid point about why Bransons might lie, but Branson is also a Corbyn/Labour supporter, so he may just be defending his train service. On the other side of the argument, whilst those purporting to ridicule Bransons claims say that the seats were in use by children or short passengers, they could only show the first couple of seats, not any more than that. Corbyn Himself justified the walk past by saying that as there were 5 in his group, he was looking for seats that would handle the group in one neat location, but that may have been an unreasonable expectation. And whilst the refuting video also showed people sitting on the floor, it doesn't tell you at what time they joined the train, so could also have been a contrived placement in the timeline.
You learn to keep an open mind in these situations.