There are niche content categories focused on fashion, fitness, or "oddly satisfying" visual media that highlight specific body parts (like legs) or equipment (tubes), but "leg on tube" is not a recognized standalone genre name.
Occasionally, "tube" (London Underground) entertainment involves unconventional physical performances or "busking" that may include gymnastic or "leg-focused" feats. However, this is not a formalized media category. leg sex on porn tube
A plaintiff suffered a severe leg injury ("broken leg in multiple places") after stopping her tube abruptly to assist her infant daughter who had fallen out during a fast, bumpy ride. There are niche content categories focused on fashion,