I disagree with this theory due to the fact the builder is the unknown or unproven part.
Buying a premium quality AR like a Colt, DD, LMT, KAC, Stag, WW... gives you confidence that the rifle will be reliable, accurate and perform and if purchased new will offer a warranty that no home built AR will ever have.
Another factor not mentioned by the guy in the video (who obviously makes his living selling AR parts) is that custom built AR rifles do not re-sell easily or for as much as name brand un-molested AR's like the ones previously mentioned.
Something to consider if you decide to upgrade after not being satisfied with the performance of your Franken built AR.
Now don't get me wrong there are those here on this site that have extensive experience building AR rifles from scratch with good success, but unless you really know the systems well, the products available even better and are sure there will be no re-sale of the AR then by all means go ahead.
My experiences have found that premium quality factory items are almost always better then custom products are when looking at the bigger picture of reliability and resale.
Another rifle not mentioned is the AR-180B-2 .223 semi.-auto. NR black rifle available for $1,500+/- a few hundred. While not an AR it might serve your purposes with Tavor or better accuracy, decent reliability and NR status.
Cheers D