[CnfsdWhtGuy]

I want to understand how this works so I am going to break this down. Hopefully you can confirm/help me understand.

Original redirect - RewriteRule ^member/([0-9]+)-(.*)$ member.php?$1-$2 [R=301,L]

New New redirect - RewriteRule ^forum/(.*)/(.*)/([0-9]+)-(.*)$ showthread.php?$3-$4 [R=301,L]

So the (.*) refers to any written title in a subfolder?

And the ([0-9]+) is any combination of numbers 0-9 in a link?

Does the $ signify the separation from the original link to the new? I almost think of it as the If x is this $(then) Y should be this?

Why is the first rule $1-$2 and the second is $3-$4?

And finally I am assuming this [R=301,L] is what is telling the server it is a redirect. correct?