I'd like to replace the player in a small web page video player script.
The script has a swfobject.js file and it's my understanding that it may be just a matter of uploading the new player swf to my webspace and then editing the js to point to the new player. I don't know how to open a .js file, and this may be too small of a request for a freelancer. Can someone help me with this?
Any guidance will be appreciated.

A .js file is simly a Javascript file. If you're used to seeing this:

<script type="text/javascript">
alert("hello!");
</script>

The same thing could be written inside a .js file:

alert("hello!");

To use the .js file inside your HTML page, use this in the HEAD section:

<script type="text/javascript" src="yourscript.js" ></script>

As for replacing the player, you can just replace the .js file, if that's all the player needs. If it's just a customization issue, just look through the code and change values around to get what you'd like. You could probably post it here and have someone to look at it for free.

Just to add in on Scott's explanation. A .js file is just a text file. You can open it in any text editor. Chances are, however, that the code within the file has been minified, meaning that unnecessary spaces, line breaks and comments has been removed and long variable and function names has been renamed to shorter ones (like a, b, c etc.). It's still a plain text file, just very hard to read and understand.