Weight, inflation, & speed all affect how much & how rapidly the tire sidewall flexes (which affects how much heat is generated). It shouldn't be a problem with good casings, but if you know your tires are marginal they don't need much excuse to let go especially when the ambient air climbs above triple digits.
The first trailer I bought started blowing tires left and right as soon as I put a decent load on it. I reckon when people go to sell something, and it has decent tires on it, they are likely to pull the decent tires off and throw on whatever they have lying around. I think he had an old, mismatched, problem tire problem. Not a recap problem.
Oh, good news ! He has an update video and at 5:30 he says he listens to Kevin Rutherford. So I'm sure he will be a master in no time.