/tmp is, as name might indicate, for temporary files. Do not store any data there, as it can be removed. Also, you probably do not need 100 Gb for temporary files.
Remove the /tmp entry from /etc/fstab. That way, /tmp will be just on the root partition (the one with the system files), and you will be able to use your 100 Gb partition for something else.
To do that, open a terminal and type
sudo cp /etc/fstab /root/fstab.backup
This makes a backup of your current fstab, should anything go wrong.
gksudo gedit /etc/fstab
Locate the line containing
/tmp and replace
/data. Save the file.
Make sure that /tmp has the correct permissions:
sudo chmod a+rwxt /tmp
Create the mount point for data:
sudo mkdir /data
Now, your 100GB partition will be mounted under /data, and the contents of it will not be removed.
To use it as user, you need to give yourself permissions to write on this partition. For example, create a directory and change it's ownership to "muhammad" (assuming that is your username):
sudo mkdir /data/Videos
chown -R muhammad:muhammad /data/Videos