1) From the video, it's hard to be 100% sure, but I think you were a bit late to prepare your slice to be sure it'll go in. If you play with Elite controls, then it's sure it was not enough.
2) This strike does indeed look very strange. It seems to be a completely missed banana shot that is somehow hit with a slice animation. If you have the .dmo, you can send it to me and I'll check what happened there...
I played with this guy who usually does the weird slice shot to the end of the court with big bounce, i always give it back, but its annoying to be using it, he told me, he just tap the slice button and press down. i let him use it because i always put him a 6-0.
It would be nice if you fix that weird shot.