I'm doing a 5.1 surround sound video presentation that cannot be interrupted and cannot crash. I'm using a projector. What is the safest and most stable way to do that? MacBook Pro? Tablet?

The real answer is a DCP with a compatible player. It's how films are delivered to cinemas. It's an MXF file, which itself is a series of JPEG2000 frames, plus a multitrack WAV file.

Barring that, PlaybackPro is widely used in the corporate even world. 90% of the time I see MacBook Pros used, mainly because it's a Mac only program. Once I saw an iMac, but that's overkill in my opinion.

Burn the video on a DVD / Blu-Ray, do a bit-wise comparison test of the burn, then test it on a dedicated hardware video player and if all is well use that device and disk in the presentation.