I have no idea when the BetterLesson team deployed this feature, but it's great. Essential, even, for this kind of site and the implementation is exactly what I would expect:
One click and you have the lesson plan in PDF and all the supplementary files in a folder on your desktop:
However finely they've tuned their downloading, the upload procedure still encourages teachers to share content standards, worksheets, and pacing guides, which, unless I'm wrong, aren't anything that will set a community of teachers ablaze. My persistent impression is that creative educators will feel constrained by BetterLesson.