datitisev and @Justoverclock in case anyone else comes here asking:
I think this is @murdocklawless’ issue. You can’t use best answer and this extension together or link preview breaks.
@murdocklawless, disable best answer, and enable Hashtag. I bet link preview works. I think we already discussed this. I feel like it is likely more best answer’s fault. Not this extension. Because best answer is more complex, so there’s more of a chance it is conflicting with other extensions like this one.
Now, the Twitter embed thing is likely different. I think that is caused by the regular expression.
This regular expression which I very thoroughly researched and was used in this extension for a long time before @Justoverclock replaced it recently, ignores URLs:
It also works with most languages. Although some have said it doesn’t work with theirs. But, I’ve never been able to verify that. According to what I read, it should work with all languages. It’s saying to include all Unicode, and marks.