No need to wreck your stem. Try drilling out the bolt in the topcap. Even if you have to trash the bolt and cap you can likely replace them at little/no cost at a friendly LBS. If your star nut is stripped you can push it further down into the steerer and replace it with a new one.

All this assuming a threadless setup, of course. Let us know how it works out.

Edit: Just watched your video. Try loosening the stem so that it's easily moved. Then, as you turn that bolt in the top cap pull up on the stem to put some pressure on the top cap and bolt. You may be able to get the bolt to engage enough of the starnut thread so that it can be backed out. Otherwise drill away.

Good luck. You should be back on the road soon enough.