Support for video embedding

[DLu]

Description

Based on feedback in #546, I spun the video embedding out into this PR, which

• Copies the source code from sphinx-contrib/video directly. I was unable to figure out the proper way to install a dependency on the upstream extension.
• Moves the video file in question to the static folder, because the above extension doesn't seem to copy it to the destination folder like the image extension does.
• Updates the embedding by directly embedding the HTML required for the video to play

~Its not the most elegant solution, but it works. I welcome feedback on how to make it more elegant. ~

Checklist

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[felixvd]

Thanks a lot for putting in the effort! I love that the video seems to work, and I don't mind the file living in static necessarily, but copied code needs to be maintained, so I'm wary about that.

I'm not familiar with the build process, so I'm not sure what you mean by install a dependency on the upstream extension. Wouldn't it work if you add the install instructions for this extension to this script?

[DLu]

I am just learning my way around sphinx. There seems like there should be a way to link to the released extension simply by adding sphinxcontrib.video in the conf.py, but that requires that the extension is on the path somewhere and I'm unclear what the sphinx way to do that is. Add a git clone to the html_proofer script?

[felixvd]

I don't know myself, but you can probably try what works in a master-source docker container.

[AndyZe]

I'll just mention, one of the tutorials already has an embedded Youtube video.

https://ros-planning.github.io/moveit_tutorials/doc/realtime_servo/realtime_servo_tutorial.html

[DLu]

I've updated this so that the video loops forever like a gif would.

When I built it locally using the ./build_locally.sh script, the generated html is

<p>You can use the <strong>Joints</strong> tab to move single joints and the redundant joints of 7-DOF robots. Try moving the “null space exploration” slider as shown in the animation below.</p>
<video width="700px" nocontrols="true" autoplay="true" loop="true">
<source src="../../_static/rviz_joints_nullspace.webm" type="video/webm">
Illustration
</video>

[felixvd]

The directory/location might not technically be the cleanest way to write it, but if it works I'm happy with it.

edit: I'm aware that I wrote the location first :) Just saying.

[DLu]

I believe CI would pass for this now that #556 is merged.

[rhaschke]

Closing and reopening to trigger CI.

[davetcoleman]

Seems like this has been greatly simplified, for better or worse :-)

[davetcoleman]

@DLu this is probably worth adding to the repo README on best practice for embedding video/gif, so we don't go through this again