[tvrain] Support authentication

[korzhe]

Before submitting an issue I checked

• I've verified and I assure that I'm running youtube-dl 2017.07.23
• At least skimmed through README and most notably FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones

Purpose of the issue

• Site support request (request for adding support for a new site)

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Description of the request:

Please add the authentication for tvrain.ru

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Output:

$ youtube-dl -v -u email_should_be_here -p password_goes_here https://tvrain.ru/lite/teleshow/lectures_on_the_rain/komu_stoit_igrat_s_kriptovaljutami_pochemu_meditsinskim_vuzam_ostalos_nedolgo_i_chto_my_budem_delat_esli_nas_zamenjat_roboty-438368/
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'-u', u'PRIVATE', u'-p', u'PRIVATE', u'https://tvrain.ru/lite/teleshow/lectures_on_the_rain/komu_stoit_igrat_s_kriptovaljutami_pochemu_meditsinskim_vuzam_ostalos_nedolgo_i_chto_my_budem_delat_esli_nas_zamenjat_roboty-438368/']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2017.07.23
[debug] Python version 2.7.12 - Linux-4.10.0-27-generic-x86_64-with-Ubuntu-16.04-xenial
[debug] exe versions: ffmpeg 2.8.11-0ubuntu0.16.04.1, ffprobe 2.8.11-0ubuntu0.16.04.1
[debug] Proxy map: {}
[generic] komu_stoit_igrat_s_kriptovaljutami_pochemu_meditsinskim_vuzam_ostalos_nedolgo_i_chto_my_budem_delat_esli_nas_zamenjat_roboty-438368: Requesting header
WARNING: Falling back on generic information extractor.
[generic] komu_stoit_igrat_s_kriptovaljutami_pochemu_meditsinskim_vuzam_ostalos_nedolgo_i_chto_my_budem_delat_esli_nas_zamenjat_roboty-438368: Downloading webpage
[generic] komu_stoit_igrat_s_kriptovaljutami_pochemu_meditsinskim_vuzam_ostalos_nedolgo_i_chto_my_budem_delat_esli_nas_zamenjat_roboty-438368: Extracting information
[EaglePlatform] 779174: Downloading JSON metadata
[EaglePlatform] 779174: Downloading m3u8 JSON
[EaglePlatform] 779174: Downloading m3u8 information
[EaglePlatform] 779174: Downloading mp4 JSON
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on u'https://stor9.servers.eaglecdn.com/tvrainru/20170629/8f6d210ffedd9_video_720p.mp4?account=tvrainru&e=1501005930&st=5Kli7tQfr8JaX5qU0m8K9A'
[download] Destination: греф демо-779174.mp4
[download] 100% of 12.72MiB in 00:01

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Other information

I provided account credentials in email to @dstftw with the subject Needed credentials for youtube-dl issue #13738. Can provide it to other developers upon request

Thanks in advance!

[hryamzik]

@korzhe FYI you can still download full videos using cookies.

This issue is related to #13557.