Newby here to the sight and wondering about your engine, is it basically stock or are there any power or performance enhancers on it - camshaft, pistons, heads or head work? Generally higher than stock stall converters are utilized to let the engine build power in within its power band- such as with a enhanced or performance cam shaft, generally something with greater than a 107-110 lobe seperation on the camshaft. I don't know about the specifics of your build but the other thing to consider is that higher stall converters also develop higher trans temperatures so you should think about adding an additional trans cooler in line with the factory set up.
Newby here but wanted to chime in on that noise. I noticed in the video your running the roller rockers with roller tips on them, are they the bushed style or individual needle bearings on the fulcrum? I've seen a lot of these aftermarket rockers develop cracks around the fulcrum area - some of the aluminum ones I've seen from china with roller bearings are pretty soft aluminum and have no liner between the rocker casting and the small needle bearings and they wear out the aluminum castings developing a lot of slack on the rocker. The other potential is the roller tips on them, if the pin is not sufficient or hearty enough it can distort, bend or wear in the rocker casing, especially if your running a pretty high lift cam or have high spring seat pressures. I would check your valve train as others have advised. Sounds like valve train noise especially as it has been progressing in your videos from what I can tell. If nothing else it would give you a chance to check the rest of the valve train - push rods, colasped lifters and such.