You need a minimum of 10 hours solo to get your first private pilot license (either single or multiengine). So according to the FARs, you can solo in a multiengine, the problem is I don't know of an insurance company that will insure a pilot to fly a twin without already having a multiengine rating. Which is why everyone I know that has a ME rating does their solo in a single, gets their private, and then the required training to add on a ME rating (which doesn't need solo time).
If you look at this video
in the aerial video it looks like the plane went off the end of the runway at 45 degrees to the runway.
It's looks like it's closer to being lined up with the taxiway that crosses 17L on the way to 17R.