No need to get offended by what he said, he was just giving you feedback saying that you would most likely not get a good response unless you post what you have attempted/have so far. This isn't really a place to have people do things for you, its a community of people helping/learning.
That said, I am not entirely sure how you should tackle this, and not a linux guru, but my first thought was something like this:
##EDIT: I like my second one better.
This will list out the poster and movie as it comes across them. But I am pretty sure after writing this, there is some logical flaws with doing it this way.
for file in $rdir
for i in "$ndir/"*
if [[ $i == *.jpg ]];then
echo "poster is $poster"
if [[ $i == *.m4v ]];then
echo "movie is $movie"
Then I was thinking about what you were doing with Find, and thought maybe something like this:
I left in the echos, i was just using them to test.
find /tmp/grabtest/ -name *.m4v > /tmp/m4list
while read line;do
echo $line is found
#HTML to link to file could be here
echo "<a href='$line'>$name</a>" >> /var/www/index.html
if [[ -f $poster ]];then
echo "poster exists"
#do whatever HTML you need.
done < "$file"
These are pretty crude examples, but should give you at least an idea. I am at work right now, so I was trying to speed through it.
Hope it helps,