Thoughts on this video?

 My guess one of the reasons he was loosening up was the play started out in a very non confrontational way were the ferret is skittering around under neath sheets and this allowed Bailey to take on the role of the chaser.  When you mention the ferrets approaching him in other scenarios Bailey probably feels more insecure then since the ferrets are mostly likely inviting their little furry selves right into his personal space.  Ferrets give off a different vibe than most small furry critters because they do not move like a prey item would despite their little size.  They are predators at heart and thus have a very confident air to them and aren't afraid to go pouncing on a dog ten times their size.  I've seen many a cat or dog that would normally love to chase something resembling a ferret turn tail when what they thought would be a tasty furry meal comes bounding at them, mouth open, back arched, and without the slightest bit of fear.  The only thing that would worry me with play between Bailey in the ferrets is despite how durable ferrets can be, is there is still a large size difference.  That adds a certain amount of risk to the play even if both parties are in agreement.

 I've been a long time ferret owner and I greatly restrict interaction between the ferrets and dogs. There is just too much of a size difference and communication difference between them. Most of my dogs have never been up close and personal with the ferrets and even the "ferret safe" ones are never trusted. Ferrets very much do invade dog's space without thought and don't understand dog warning signals such as growling, showing teeth or snapping. And even with dogs who are very tolerant the size difference IMO puts them at risk of accidental injury. I know plenty of people who allow their dogs and ferrets to interact and everything is fine. I also know that ferret lists and forums all have posters who have had their ferrets killed by their dogs and that often it is a dog who "was always fine" with the ferrets.

 I had a ferret killed by a foster dog a few years ago. The ferret got out and was able to get into the foster dog's pen (she was in an expen part of the time). This dog always seemed good with small animals but of course, I'd not have ever trusted her with a loose ferret. She had fatally injured the ferret (a large intact hob) within a second. I couldn't have stopped it even if I had been just a few feet away because all it took was one grab - he didn't even have a mark on him.