@melanie It is much better to use the default item video tab to insert the video into the k2 item.
Please read
getk2.org/documentation/tutorials/item/174-templating-with-k2-and-the-concepts-of-sub-templates
After creating an override you should be editing the file:
YourSiteRoot/templates/YourTemplateName/html/com_k2/templates/YourTemplateName/item.php

you will have to create the proper file folder structure and then copy the file into it

If you're using JW All Videos plugin, please check if it's Enabled. Extensions -> Plugin Manager

Hi both,

Hi,

many thanks for responding.

I am kind of getting there. I tweaked the file you suggested but it still didn't work for me. I am not sure what template override is, and a little confused about what file structure to copy (i am a newbie to K2).

Anyway, I finally got my video to play at the top of the article using this code typed in the position I wanted it to be:

{mp4}mytestvideo{/mp4} this works

However, I need also to add a preview picture, so I added the extra detail:

{mp4 img="mypreview.jpg"}mytestvideo{/mp4}

But it doesn't like it and now just shows the text.