Man, the Austin & Ally and Jessie crossover was such a blast from the past! I totally geeked out when it first aired. If you're hunting for Part 1, Disney+ is your best bet—they’ve got pretty much all the classic Disney Channel content in one place. I rewatched it there last year, and the nostalgia hit hard. The chemistry between Ross Lynch and Debby Ryan was hilarious, especially with the whole 'Austin babysitting the Ross kids' chaos.
If you don’t have Disney+, you might find clips on YouTube, but full episodes are tricky due to copyright. Some folks upload edited versions, though. Fair warning: quality varies, and you might stumble into spoiler-heavy comment sections. For a legit route, check digital stores like Amazon Prime or iTunes—sometimes they sell individual episodes. Just make sure to search for 'Austin & Ally and Jessie crossover' specifically, or you’ll drown in unrelated results.