Original Question

The Firefox help pages state:

After you click on the media on a web page, to give it focus, you can control the playback with your keyboard.

But how can we initially give it focus if we are not using a mouse

Edits

Since I cannot provide a link to the video page, here is the relevant page source:

<div class="my-account">

    <p class="back-link">

        <a href="https://shop.dananddave.com/streaming/customer/products/">

            <small>&laquo;</small>Back to My Streaming Videos</a>

    </p>

    <div class="page-title">

         <h1>The Unreal Work, vol. 1 - <span id="streaming-link-titile">PaulWilson</span></h1>

    </div>

    <div id="my-streaming-product">

        <iframe src="https://player.vimeo.com/video/55133774?show_title=1&amp;show_byline=0&amp;show_portrait=0&amp;color=000000&amp;fullscreen=1&amp;autoplay=0" height="100%" width="100%" frameborder="0"></iframe>

    </div>

    <div class="buttons-set">

        <p class="back-link">

            <a href="https://shop.dananddave.com/streaming/customer/products/">

                <small>&laquo;</small>Back to My Streaming Videos</a>

        </p>

    </div>

</div>

If the video element has the controls attribute (i.e., Firefox shall use its own control menu), you can use Tab to focus the video player. When it has focus, you can use the keyboard controls.

If the video element doesn’t have the controls attribute, it’s the author’s responsibility to provide a control menu – and then you’d have to hope that the author had keyboard accessibility in mind.

However, for such a video it might work to focus the player (with Tab) and open the context menu (for example, via Shift+F10), where you can enable the default controls. After this, it should be possible to use the default keyboard controls. (I couldn’t test it with many videos, so it might depend on the author’s script.)

press Tab repeatedly until the video is focused then press context menu (looks like a box with three lines) to get controls like play and pause or use the keyboard shortcuts provided by firefox