用于验证输入的youtube或soundcloud url的正则表达式具有正确的语法

Question

I am doing this in laravel php framework. Here is the relevant part that does the validation:

$this->validate($request, [
      'portrait_url' => 'required|active_url|regex:https://soundcloud.com/*',
      'video_url' => 'required|active_url|regex:https://www.youtube.com/user/*',
    ]);

Unfortunately I get the error that says:

preg_match(): Delimiter must not be alphanumeric or backslash

I think I am not writing my regular expression well. A hint please on the right regex pattern to accomplish my purpose. Particularly for youtube I want to verify that the entered url is the one that looks like this: https://www.youtube.com/user/OfficialSinach the phrase OfficialSinach could be replaced by any other username depending on the user being accessed.