Most video editing software will allow you to turn the footage to any angle you need, so it's just a matter of uploading the fotage and editing it. The only problem with that is that you are going to either have a smaller picture with bands on either side, or a full screen close up, and a visible loss of quality and chopped heads and legs.
Cheapest is to use windows movie editor, free with xp and later. On the left look for "Edit Movie" and click on "Show Video Effects", and scroll down the video effects window to "Rotate 90" and just drop it into your timeline. Sorted.
If you don't fancy doing it yourself then any videographer will do this for you... but it'll cost you.