RewriteEngine on

RewriteRule ^(small|big)_photo([0-9]+)\.jpeg$ photo.php?id=$2&size=$1 [QSA,L]

RewriteRule ^(small|big)_ava([0-9]+)\.jpeg$ avatar.php?id=$2&size=$1 [QSA,L]

RewriteRule ^(small|big)_videosrc/(.*)\.jpeg$ video.php?path=$2&size=$1 [QSA,L]