Photoshop elements wont let me start video

Photoshop Elements and Premiere Elements are two different programs.  You have to purchase a license for each one.  They are generally sold as a discounted bundle.  So, if you only purchased Photoshop Elements but want Premiere Elements too, I suggest you contact Adobe Support to sort it out for you.

You can start a chat session by going to the Contact Adobe Support page.  Make sure you are signed into your Adobe account and try typing Agent when the chat window opens. (If you use my link, the chat window should open automatically.)

You need the video editor- which does not come with with PSE 2025.  From what you stated earlier that is the case:  You only purchased Adobe Photoshop elements, and did not purchase Premeiere Elements.    Once you install the trial you then can click on the same link you've tried in the past:  you will be prompted to continue the trial, or puchase it.

Beginning with PSE 2025 there are no more serial numbers to worry about, AND the software witll stop working 3 years from when you purchase it.

Here is a link to a 7 day trial :

https://www.adobe.com/products/premiere-elements/free-trial.html