HTML5 video tag attributes

[georgringer]

If you try to add to the html5 media element the attribute preload="none", it doesn't show up on the frontend.
In /sysext/frontend/Classes/ContentObject/FlowPlayerContentObject.php between the lines 389-393:

        foreach ($this->html5TagAttributes as $attribute) {
            if ($conf['attributes.'][$attribute] === 'true' || $conf['attributes.'][$attribute] === strToLower($attribute) || $conf['attributes.'][$attribute] === $attribute) {
                $attributes .= strToLower($attribute) . '="' . strToLower($attribute) . '" ';
            }
        }

The attribute preload is not allowed with the value "none" and the custom value will not be used.

copy of https://forge.typo3.org/issues/66853