Cool! Some nitpicks though:
>Wouldn't it be easier if I actually got the cape on the last room of the level rather than waiting for it to feed baby Yoshi? Could be me. Related, the yellow baby Yoshi wasn't needed at all since you can wait for the koopa to get out of the way and progress.
>Some sprites can disappear, like the spiny or half of the Chuck, prolly due to the Wigglers at the top of the level. Did you make sure you used the correct sprite header? On the worst case scenario, you could use this
>At 1:05, you can feed the baby Yoshi one of those two berries before reaching the ropes.
The preview level looks nice btw.