Truck won't start, engine turns over..see video

Ok, looks like that is the 4.3L engine, right? There are several things to be checked. How do you want me to proceed, since you know not much of engines?

What would you check first and in what order would you do it? Thank you.

Let me know what size engine it is for sure. First check for spark by pulling a spark plug wire and putting a spark plug on the end of the wire, lay it down on something metal on the engine, and have someone turn the engine over as someone watches for a spark at the plug end. Next would be to check fuel pressure with a fuel pressure gauge at the schrader valve on the intake manifold. It should be 56 to 63 lbs. A fuel pressure bleed down test next is just watching the gauge to see if it drops in pressure. It should not drop more that 5 lbs. in 3 minutes from the highest reading. Once you get these things done let me know and we can go from there.

Thank you! The engine size is 5.7 L