Thanks to a 15-minute video recorded and uploaded by forum member DinnerSonic, we can now see how this level looks like in its entirety. Using a ripped version of the game and an emulator, he filmed every little bit of the level.
Being a test level, most of it is designed to test out the game’s physics on how Shadow controls on loops, slopes, steps, and half-pipes among other structures. There’s also the odd laser object, mostly due to triggering some flags in Westopolis.
There’s still no video of the other test level, but if you keep an eye on the forum thread, one may just pop up sooner or later.