BuddyPress.org

For BP_AVATAR_URL, try:
http://example.com/wp-content/blogs.dir/1/files

For BP_AVATAR_UPLOAD_PATH, you can try the snippet posted by 3dperuna:
https://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/bp-1-2-4-custom-bp_avatar_url-change/#post-56257

But in some cases, that isn’t accurate. Only you can enter in the correct filepath.