Actually, Peter, I was sorta’ thinking of other videos as Tim's videos weren't too bad. But listening to Tim's Copland video here, I'd say Tim’s videos certainly fall into that same questionable category.
Here’s my flavor of I think the same interpretation as Tim’s.
Listen to the bass notes for the first 20 seconds or so of either video. At around the 14 sec mark the bass on Tim’s video gets quite unmusical. With Tim's Copland video you should hear a rather odd bass as though it’s broadcasting from a deep dark tunnel and my ears are trapped in the same tunnel for greatest effect. That’s Tim’s room you’re hearing and those poorly-defined bass notes cannot be found in the recording. Not to mention the bass is greatly exaggerated. Tim's mids and highs seem much less scathed by this effect and sound musical.
Some may like or prefer this type of bass perhaps because that's what they hear in their own room. But I can assure you you'll never hear this type of bass live in a concert hall. To confirm all one needs to do is find and listen to the "official" youtube flavor.
Since we all have listening rooms and since no speaker/room interface is perfect, we all experience these same effects to one degree or another. Obviously, the goal is to absolutely minimize such effects. But that's what they are - effects. Even Tim's Copland video's bass is much better than some of others' videos.
Some may think Tim's video sounds warmer, richer, cozier, more musical sounding than my video which in comparison may come across as a bit thin or lean. But with such effects on Tim's bass regions and elsewhere, before determining which is more genuine, one needs to ask, are they hearing what's embedded in the recording or are they hearing what's embedded in the recording plus a good dose of the room?
If we're hearing a good dose of Tim's room, that inherently implies added warmth, richness, tonality, etc. because our rooms are tiny compared to the concert hall. And too many times it seems we confuse this room-induced warmth as being more musical. Especially if we hear similar sounds on our own configs. But such sounds are never heard in a sufficiently tuned concert hall or recording.
As I've mentioned before, it's kinda' like the sound of a bouncing basketball in a small fully furnished and carpeted walk-in-closet vs the sound of a bouncing basketball in a full-court gymnasium. One will sound warmer, richer, etc than the other but as we know a basketball's natural habitat is the full-court gym - not the walk-in-closet. Not the best analogy but I hope the point is made.
If you have a macbook and headphones I suggest volume level is 2 maybe 3 notches below max volume for best comparison.