It looks, to me, like lipid nanoparticles (or microparticles/ microdots) pooling along the walls of veins, stopping them up... The elasticity is what makes me think this is the case. Scientists working with la Quinta Columna, from Venezuela (and maybe Brasil?) have discussed how the manmade lipids are drying and hardening when they are warmed to room temp. I think it happens even more quickly when temps are at about 98 degrees ...
So, yeah, looks like a vein (i thought so, too), but is a bit too rubbery for venous tissue.