This PR adds a configuration option to control the preloading of video data on
page load with the HTML5 'preload'[1] attribute on the `<video>` element.
The option is enabled by default, meaning that the `preload` attribute's value
will be 'auto'. If users want to prevent preloading of video data, they
can disable the option, which will set the attribute value to 'none'.
[1](https://www.w3schools.com/tags/att_video_preload.asp)
Closes issue 4110
This PR adds two new config option, to pass a PO token (config 'po_token') and
a visitor ID (config 'visitor_data') to Youtube. These two strings are required
to play videos using the WEB client.
Warning: These strings gives much more identifiable information to Google!
If the po_token setting is filled in, then the WEB client is used. If not, the
Android client is used. TvHtml5ScreenEmbed will still be used as a fallback.
Script for generating po_token and visitor_data:
https://github.com/iv-org/youtube-trusted-session-generator
Helps with issue 4734
Fix#4110 by adding an option to control the preloading of video data on
page load. If disabled ("false"), the browser will not preload any video
data until the user explicitly hits the "Play" button.
If enabled ("true"), the default behavior will be used, which means the
browser decides how much of the video will be preloaded.
Unlike the other migrations, this one uses a bare table name to specify the table. This means it looks in the default search path. Unfortunately, the out of box search path is:
1. Schema with the same name as the user
2. Public
Because of this, if a schema exists with the same name as the DB user, the playlist_videos table will get created in _that_ schema, rather than the public schema, and then the grant statement will fail with an error like below if check_table is enabled as it keeps trying to create the table but failing on the grant statement:
```
2022-01-22 02:27:42 UTC [info] check_table: check_table: CREATE TABLE playlist_videos
Unhandled exception: relation "public.playlist_videos" does not exist (PQ::PQError)
from /usr/share/crystal/src/primitives.cr:266:3 in 'handle_error'
from lib/pg/src/pq/connection.cr:184:9 in 'handle_async_frames'
from lib/pg/src/pq/connection.cr:162:7 in 'read'
from lib/pg/src/pq/query.cr:53:14 in 'exec_all'
from lib/db/src/db/database.cr:126:9 in '__crystal_main'
from /usr/share/crystal/src/crystal/main.cr:110:5 in 'main'
from src/env/__libc_start_main.c:94:2 in 'libc_start_main_stage2'
2022-01-22 02:27:43 UTC [info] check_table: check_table: CREATE TABLE playlist_videos
Unhandled exception: relation "public.playlist_videos" does not exist (PQ::PQError)
from /usr/share/crystal/src/primitives.cr:266:3 in 'handle_error'
from lib/pg/src/pq/connection.cr:184:9 in 'handle_async_frames'
from lib/pg/src/pq/connection.cr:162:7 in 'read'
from lib/pg/src/pq/query.cr:53:14 in 'exec_all'
from lib/db/src/db/database.cr:126:9 in '__crystal_main'
from /usr/share/crystal/src/crystal/main.cr:110:5 in 'main'
from src/env/__libc_start_main.c:94:2 in 'libc_start_main_stage2'
```
