i dont know if its a website error, but the am4 one is broken and does not play.
Yeah, something's borked with the "Play SPC" button on this song here. When I attempt to click it, the SPC player appears, but doesn't play. The next time I attempt to do anything with the SPC player, I get an error stating "Couldn't load SPC player.". After that, the player lingers in the lower-right corner, and I can't remove it. Also, my mouse cursor on this page tends to get stuck in "hourglass" mode.
Fortunately, leaving/refreshing the page removes the wonky effects, but attempting to "Play SPC" on this song still doesn't work and causes the oddities to return until I refresh/leave the page again.
EDIT (May 9, 2020): Seems that "Play SPC" works correctly now.