How come this one line of htaccess isn't work?

RewriteEngine On
RewriteRule ^([^_]*)\.html$ /oops.php?videoID=$1 [R=301,L]

Am I doing anything wrong?

 

And what are you trying to do?

 

Thanks, an example would be changing:
/oops.php?videoID=3416

to
/POSTNAME.html

Wouldn't the above .htaccess covert it?

 

But you don't know the post name this way, all you can do is http://domain.com/12345.html where 12345 is a numeric ID of your page.

 

What I can infer is that you are trying to respond to the request VIDEONAME.html using /oops.php?videoID=VIDEONAME

A basic shortcoming might be using this regex

# ^/([^_]*)\.html$ instead of ^([^_]*)\.html$
RewriteRule ^/([^_]*)\.html$ /oops.php?videoID=$1 [R=301,L] 

Code (markup):

Secondly, it is necessary (or at least a good practice) to define RewriteBase

RewriteEngine On
RewriteBase /relative/deployment/url

Code (markup):

Irrespective of all this, I feel that it is much easier to tackle all this using the $_SERVER available in PHP
The general wordpress .htaccess redirects all requests to the index.php in your deployment folder. You can now detect the requests from

$_SERVER['REQUEST_URI']

Code (markup):

and define redirections. MVC Architecture seems apt in this scenario.