Thanks Stella for setting this issue straight. Looks like it was from a stage and NOT from a rest day ride.
This has been done to death. The photo of LeMond ripping a FRONT tub off is from the rest day. The clip you post is of the stage later in the race when he had a REAR puncture.
I stand by my original comment.
Thierry Mertens wrote 'We, Greg LeMond Fans, did a research on this picture. It took us a long time to figure out what is going on here. It appears that this is from the stage where Greg had a flat on the Col de Marie Blanque. I also thought this for a long time and it's normal everybody does. But then we were looking at the details of the picture. Greg is dealing with his front wheel and uses a tool from his little sack (black thing on the ground). He carried that when he was on training. There is no bottle on the bike. Even he's not wearing gloves. The environment is also different. I have pictures of the stage where he had a flat and it was not like that. But the biggest difference is his wheel. He had a flat at the rear wheel during the stage. This one is the front wheel. This picture was taken during a training ride on the rest day in the 1990 Tour de France. Some journalist took this one and published it in the magazines. We verified it and we are right with our study. More details about this was already written here a few years ago. Just search in the pictures to the same pic . There are others about that stage. The comment says enough. A mystery was solved for us.'