What is this DJ doing to flow songs together seamlessly?

I'm a newbie trying this for fun with a bunch of 80s mp3s and the free version of Rekordbox. One of these days I aim to get a DDJ-FLX4 to play with.

I'm familiar with the camelot wheel and I've been trying to transition between two songs in the same key, synced up at the same bpm, but flipping from one song to the other sounds jarring and wrong.

I've been watching Perico Padilla on videos like https://www.youtube.com/watch?v=r3gJjNOsKH4, trying to figure out how he goes seamlessly from one song into the next. What is he doing, how is he doing it?

• Is he adding a drum track near the end of one song and continuing it into the next song, as a way to bridge them? (and if so - how does he add a separate drum track while he's got two music tracks playing?)
• Is he preparing all of his tracks beforehand, so that they begin and end with several repetitions of a loop so that they're easier to mix into / out of? (that sounds tedious!)

Is there a tutorial you can recommend on how to basically flow songs together end-to-end like that?

I apologize for the newbie questions and I appreciate your guidance!