ttrss-yframes/init.php

<?php
class YFrames extends Plugin {

    private $host;

    function about() {
        return array(1.0,
                     "iFrames for Youtube feeds",
                     "phga");
    }

    function init($host) {
        $this->host = $host;

        $host->add_hook($host::HOOK_ARTICLE_FILTER, $this);
        $host->add_hook($host::HOOK_IFRAME_WHITELISTED, $this);
    }

    function hook_iframe_whitelisted($src) {
        return in_array($src, ["www.youtube.com", "youtube.com", "youtu.be"]);
    }

    function hook_article_filter($article) {

        // $debug = json_encode($article);
        // Match allowed links and extract "video ID"
        if (preg_match_all("/.*(youtube|youtu)\.(com|be)\/watch\?v=([\w\d_-]+).*/i",
                           $article["link"], $matches, PREG_PATTERN_ORDER)) {

            if ($matches[3][0]) {
                $link = "https://www.youtube.com/embed/" . $matches[3][0];
                $attributes = "width='819' height='460' class='youtube-player' allowfullscreen";
                $yframe = "<iframe src='$link' $attributes></iframe>";

                $article["content"] = $yframe;
            }
        }

        $description = str_replace("\n", "<br/>", $article["enclosures"][0][3]);
        if (strlen($description) > 0) {
            $article["content"] .= "<br/>" . $description ;
        } else {
            $article["content"] .= "<br/>No video description available.";
        }

        return $article;
    }

    function api_version() {
        return 2;
    }

}