There is a thread on rsd about a clip of the day on ultivillage about whether a throw is a travel.
There is another factor at work here in determining the callability of the travel. I am distinguishing callability from legality here.
What makes a violation likely to be called? Two that spring to mind are:
1. Egregious violation
2. Clear advantage
2a. Breaking the mark
2b. Getting power on a huck
Some will argue about whether 2b is worthy of a travel call or not, and I'm not going to get into that today. But I read the commentary here, then I watched the clip, and came up with another factor:
3. Violator makes no attempt to avoid the infraction.
A defender who appears to try to avoid contact on a layout is less likely to be called for a foul than one who does not, even if the contact is the same. In this case, the hucker doesn't even seem to pay attention to his back foot. He just lets his back foot slide. It didn't drag, and it didn't simply roll over to his toe because he was exerting effort to keep it down and he made a powerful throw. A spectator or player who sees this play might intuitively feel that it's a travel not because he can actually tell that the foot moved before release, but because the thrower did nothing to prevent a travel.
I've made a few petty travel calls in my life, and have been irritated quite a few times by small travels, and I think those were due to factor #3 here. An example is the "handler hop" you'll sometimes see where a handler will catch a swing pass flat-footed and will take a little hop-step to the continue side. Beau's travels might fall under this category, too, as he walks back and forth about the same spot but isn't really setting himself up for anything.
Frank H might be on track with his belief that the soft love policies of ultimate that have allowed these routine, no-need violations to go unpunished have resulted in a less fundamentally sound game. But that, too, is a discussion for another day.