Why does my apply laptop shut off Safari when I try to watch videos online? Also why can't I use Firefox with this(I used to)

Question

Why does ma older apple laptop cancel Safari when I a m watching videos online?  Also,I used to be able to run Firefox but now message states "can't use with this operating system"?

Answer 1

You can't use Firefox, because your operating system, OS X, is a version 10.4 or earlier. 
Firefox "upgraded" its Mac compatible version, so that it will only operate with OS 10.6 or later.
Your Safari also might quit, because it too has an upgraded version with greater stability geared toward 10.4 and later.  Perhaps you are using system 10.3 or earlier.
It is also possible that Safari quits, because the video sites you watch have changed to be compatible with newer browser versions with later Flash Player compatibility, like Adobe.
It is difficult to find browser compatibility or stability for earlier than 10.4.
What the above post is showing is in the drop down menu in the upper left of your screen.  Click on the blue Apple for its drop down menu. Click on the first in the list, About This Mac. That's where you'll see the version as shown in the previous post.
If you upgraded your Safari, even that could be a problem, because it might not work as well with your older operating system.  I haven't tried the following link, but it offers the Safari versions that fit each system. You can try downloading the one that matches yours.  If that doesn't work, you can always upgrade again.
http://mac.oldapps.com/safari.php