I think the conditions and therefore the experience you get from it depends so much on when you ski it - if you go there mid January (assuming that's when he did it) then most likely it'll be fine. There should be decent snow and it'll be quiet because it's outside peak holiday time. From experience during half term it can get unbearably icy and I reckon it'd be even worse at Easter as it gets warmer - by then even the 'best' pistes in The 3 Valleys will be in worse condition than Marcassin mid-January. Great video!
Hate the run, did it on the last day of a trip back in December 2016 and when going past the cable car halfway down there was a rock sticking through the snow in the middle of the piste. Tore a massive chunk off the side of my ski.
Also I think those ridges are like a beginning stage of moguls, so where people ski the most would be in the middle of the ridges (falls in line with its popularity).
Those ridges are likely from high winds blowing snow across the slope, when the wind slows slighty the snow is deposited and the deposits build up causing ridges. You'll see much more defined ridges on the sides of pistes where the wind really picks up and blows right up the mountain.
I am not familiar with this resort having avoided France in favour of Austria. However, technology over the last 5 decades that I have been skiing has improved and pistes are no longer groomed during daytime hours. They are groomed at night. Consequently using technology from farming, the "route" is programmed and there is a very subtle area that, unless flattened during the daytime between "passes" that gives a few cm that is either not groomed or is thrown off by the rakes, macde worse if there is not heavy snowfall. Once it is skied over, particularly if well used, it will "smooth" out and create "natural ridges". Time gives emphasis to such phenomena. A huge dump of snow (50cm+) for 3 consecutive days will bring the piste bashers out during the daytime as well as the evening - in the day to groom the slopes and in the evenings to move surplus snow to preferred "banks". But hey, just conjecture from a very amateur skier and pretty geriatric to boot!
The part of the run you say is the worst is actually called Aigle, not Marcassin. Marcassin is the top part of the run you qualify as "not bad at all".
