There’s an article on this 130-year-old device at bOINGbOING, though the text adds almost nothing to the YouTube notes about this mechanical bird-song-maker:
This wind-up mechanism has a tiny bellows and several gears that produce a remarkably lifelike bird call.
Szymon Pawelec, the collector and demonstrator who consulted on the Scorsese film Hugo, says:
A mechanical singing bird mechanism. Made around 120 years ago in Paris, probably by Bontems. In the film I hope you can identify all the major parts and see them working together to make the sound. The mechanism was in a rusted and seized state and has been restored. Surpisingly [sic] the bellows are in good original condition. See our channel for more, much more.
Here’s another one. I’m still not sure how the damn things work, producing a rather complex bird call, but I have no mechanical talent for discerning these things. It’s enough to marvel at it.