The part about Isaac being an only son made no sense, because Abraham had two sons. And the YouTubist couldn’t understand how Abraham should be rewarded for sacrificing his son.
Well, the problem here is that the reader, having been corrupted by theology, thinks that Genesis is a composed book of theological statements, when in fact it is an uncomposed collection of traditional stories. We do not mind reading of Greek myths in which the stories aren’t consistent with each other, and we shouldn’t mind this in the Bible, either. If I had to interpret the sacrifice-story, knowing only the above, I would say there must have been a traditional story in which a man is told to sacrifice his only son; when the story got collected into Genesis, Abraham was made the father and Isaac the son. That elsewhere in the text Abraham has two sons isn’t important; this story depends upon the father having but one son. For, in the culture to whom the tale belongs, sacrifice of one’s son is an accepted practice; but to give up one’s only son is a hard blow, so that the father’s willingness to sacrifice that son is a test of his devotion to his god.
The Bible does not come together in a coherent way. It is a library of anthologies, with different stories, traditional tales and such, crammed into a set of available characters, and styled according to the tastes of different periods. And these periods can be quite barbaric; thus the Bible is not nearly as good as its reputation; it doesn’t really apply to modern life, except in ways for which its presentation is too primitive.