Lead strips for repairing slipped roof stones?

[rhythmstick33]

I have a stone roof and a couple of the stones have slipped, which I need to repair.

Found a YouTube video of someone doing the same repair and he used lead strips to hook around the bottom of the slipped stones. Is this still the best practice?

If so, what thickness and width of lead strips would you use and where would you normally buy them from?

Thank you!