Lightroom講座：（PhotoShopも随時追加）短時間でマスターするここまで出来ればお仕事でもOK

You can view and review the lecture materials indefinitely, like an on-demand channel.

Definitely! If you have an internet connection, courses on Udemy are available on any device at any time. If you don't have an internet connection, some instructors also let their students download course lectures. That's up to the instructor though, so make sure you get on their good side!