Add support for akvideo

[etmatrix]

Checklist

• I'm reporting a new site support request
• I've verified that I'm running youtube-dl version 2019.11.05
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that none of provided URLs violate any copyrights
• I've searched the bugtracker for similar site support requests including closed ones

Example URLs

• Single video: https://akvideo.stream/video/0bvtm479w9iw
• Playlist: no playlist

Description

I already developed an extractor, works but is not very good.
AKVideo support more formats: low, normal and high resolution.
For extract all resolutions I need to get a webpage for each format over the main get, but before generate a new url akvideo require a sleep time.
Can I extract the real url after the user choose the format?
Now I extract all urls and return the array formats.

class AKVideoIE(InfoExtractor):
    _VALID_URL = r'https?://akvideo\.stream/video/(?P<id>\w+)'

    def _real_extract(self, url):
        video_id = self._match_id(url)
        webpage = self._download_webpage(url, video_id)

        title = ''
        formats = []
        videoinfo = re.findall(r'download_video\(\'' + video_id + '\',\'(\w)\',\'(.*)\'\)".*<td nowrap *>(\d+)x(\d+)', webpage)
        for info in videoinfo:
            webpage = self._download_webpage('https://akvideo.stream/dl?op=download_orig&id=' + video_id + '&mode=' + info[0] + '&hash=' + info[1], video_id)

            movie_url = re.findall(r'<a class="dwnb" href="(.*?)"', webpage)
            title = str(movie_url[0]).split("/")[-1]

            formats.append({'url': movie_url[0], 'height': int(info[3]), 'width': int(info[2]) })
            time.sleep(3)

        self._sort_formats(formats)

        return {
            'id':          video_id,
            'title':       title,
            'description': title,
            'formats':     formats
        }