Did you try another converter? Normally that's a youtube restriction.

When you search, open the videos on another tab and it should work.

Re: @MurkBRA:
verifique se o conflito ñ é causado por outro script q vc esteja usando pro legendas.tv

Re: @MurkBRA:

ñ entendi sua duvida, aqui no firefox 49.0.2 está tudo em ordem
tente mostrar uma imagem talvez eu possa ajudar

Cool, Thank you !

I've already blocked the script, which input this frame with AdBlock Plus, so I don't need it anymore, but if you still want add support I'd be grateful.

Re: @Marti: Now it's exactly as it was previewed. Thank you, now I understood how I should do it.

When I'm on "Edit Script Info" I insert url and image links and click Preview button, and it shows

as soon as, I click Save button, the post it's not like it was previewed

and I'm using the panels buttons

Neither using html tags the post is right.
Are you getting the same issue?

When I enter this site I get the box with portuguese warning, I'm using adblock plus and should disable.

So, which one is the copy,
This or https://openuserjs.org/scripts/sebaro/ViewTube ?

Re: @pootz: Just found, here the script I had from userscript and the same author nick, trupf. https://openuserjs.org/scripts/trupf/ViewTube_GM

Re: @Marti: Thanks for answer Marti. The version I had it was from July 7, and it was from userscripts.org . The script was working very well like this. I'm sure author's name wasn't sebaro, I saw before remove it today and install this one.

First, I had this script version from July, grabbed it from userscripts, and the author's name is different. This is a re-upload or are you the real author?

Second, every time the scripts update I have to remove youtube.com from @include, because I don't wanna lose the captions feature from youtube. Since English is not my native language, on almost every English videos I watch with English subtitles. So, would be possible, in future, to have captions on html5 or choose the list of urls I'd like the script runs ?