@diegopino 

you must remove the BBCodes

<p>[video=youtube]</p>

and

[/video]

in the url

Example

//www.youtube.com/embed/eTZ55Twa__Q[/video]?start=

should look like this

//www.youtube.com/embed/eTZ55Twa__Q?start=

https://app.screencast.com/9OcOaUtZDZVyH

you can do this manually in each post 😆 

or with 2 phpMyAdmin SQL commands

Example

update wp_wpforo_posts set body = replace(body,'[/video]?start=','?start=');

and

update wp_wpforo_posts set body = replace(body,'<p>[video=youtube]</p>','');

you can also use a plugin like > Search & Replace

but make a backup before 😉

Thank you so much Tutrix for help my

in mi case, the way its via with 2 phpMyAdmin SQL commands, becasuse have hundreds of many post with youtube videos.

Do it the steps phpMyAdmin SQL commands but not work in forum:

update wp_wpforo_posts set body = replace(body,'[/video]?start=','?start=');

Anexo images preview:

@diegopino 

is the table prefix correct?

wp_wpforo_posts

Hi Tutrix

Yes, the table prefix its ok, in phpmyadmin have all tables ok with prefix.

anexo image preview:

Thank you so much for Support Tutrix 👍 

@diegopino 

try

update wp_wpforo_posts set body = replace(body,'[/video]','');

and

update wp_wpforo_posts set body = replace(body,'[video=youtube]','');

😍 Amazing Tutrix. thank you so much for support

That code via PhpMyAdmin work perfect.  
saved me a lot of work time, very happy with the support.