[YleAreena] Add new extractor

[Hegezcc]

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Before submitting a pull request make sure you have:

• At least skimmed through adding new extractor tutorial and youtube-dl coding conventions sections
• Searched the bugtracker for similar pull requests
• Checked the code with flake8

In order to be accepted and merged into youtube-dl each piece of code must be in public domain or released under Unlicense. Check one of the following options:

• I am the original author of this code and I am willing to release it under Unlicense
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What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

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Description of your pull request and other information

This pull request adds a new extractor for Yle Areena, Finnish Broadcasting Company internet service. There has been an unmerged extractor pull request for both Yle Areena and Yle Elävä Arkisto using the old Flash player technology, but that player has been completely phased out from Yle Areena and replaced with Kaltura streaming service. As the codebases of these services differ greatly now, this project's scope is limited to be in Yle Areena.

Ping @hlintala for making the old extractor. Maybe the Yle Elävä Arkisto extractor might be resurrected from your code.

[Hegezcc]

Looks like Yle is using aggressive geo-blocking which prevents tests in CI from passing. This is a major problem, as I cannot provide a really big proxy service for every downloader and also believe that the extractor's main userbase is in Finland, which would make the proxy pretty pointless.

How can this pull request proceed?

[dstftw]

Read coding conventions.

[Hegezcc]

@dstftw could you elaborate more on what is wrong in this code regarding coding conventions?

[Hegezcc]

Bump.

[Hegezcc]

Bump. Anything still required here?

[hlintala]

Maybe code should look something like

player_url = url_or_none(self._og_search_property(['video:secure_url', 'video:url'], webpage))

instead of

try:
    player_url = url_or_none(
        self._og_search_property('video:secure_url', webpage)
    )
except RegexNotFoundError:
        player_url = None

# If this backup fails extractor will error out
player_url = url_or_none(
    self._og_search_property('video:url', webpage)
)

Also trailing parenthesis probably should be located after last argument and not on a new line.

[subirax]

Bump. Thanks!

[tpimh]

What's actually left to be done to merge this? I can provide a proxy service for CI to run if required.