This is a fascinating discussion. It seems that in spite of all the variegated views, the vitriolic nature of previous debates hasn't surfaced here. That is commendable, in my opinion.
To weigh in, I concur that usually, in-person lessons are best. But I have also been involved in situations where trumpeters could not get to a teacher for various reasons. I have helped a few students, sight unseen, using my best sense of what was happening.
I also would agree with Pops, that a cyberlesson from someone who knows what's going on is better than many in-person lessons from someone who does not. And anyone who has monitored TPIN for more than a couple of weeks will recognize that Pops' posts are among the most well conceived, analyzed, thoroughly argued, and informative to come from this august body.
In addition, I agree with Pops in his contention that there is much that passes for trumpet instruction that is unproductive, to say the least. Certainly, there is excellent teaching available. But there is still an awful lot of garbage which passes for knowledge. Currently, I have 5 students who were not schooled in taking or using a proper breath, (either in size or manner) and who had flimsy embouchures.
P.S. Pops, the bit about pleasing the dean, the senior music faculty, the band director, and whomever else was priceless.