Hi Andrei,
Ordinarily, you’d have a video switcher with keying capability, feed the graphics to the switcher as a separate source, and let it add in the graphics for you; it’d also be possible to get a standalone video “logo inserter” that would do the same thing, downstream from your video switcher.
That said, I assume from your posts that your event is pretty straightforward and budget-constrained — one camera, one projector, and nothing else. Please correct me if I am wrong!
So if your question is, “How can I use my Macbook Pro to add a static graphic over live video from my DVX100a?” then the answer is a product like Boinx TV (if you want a well-packaged solution) or Quartz Composer (if you want to create your own, a la Max or Jitter).
That said, there are a couple other considerations.
Redundancy is vital in live events! I always run backups for computer sources on live events. Ideally, if you do use your computer for this, you would have a second computer running the same thing and a video switcher in case your main computer crashes. If you insist on using only one Mac, you should also send video directly from the camera to another input on the projector so you are covered in case the computer crashes.
You haven’t mentioned lighting and audio, and both will be important. I don’t know what you’re considering for audio, but you might want to rent an audio delay unit to compensate for the delay in video due to processing in order to preserve lip sync.
Walter Soyka, Principal
Keen Live, Inc.
Presentation, Motion Graphics & Widescreen Design
RenderBreak: A Blog on Innovation in Production