The $p->video now return the video link only, to get the video ID we can use get_video_id($p->video); and call it from the theme.
For Upgrade Only
If you are not using theme shipped with HTMLy source code, please download the updated version. If you already modify the theme and don't want your changes to be lost, simply update the <?php echo $p->video;?> to <?php echo get_video_id($p->video); ?> in main.html.php and post.html.php.
If you can't save the date format, please rename the time.format to date.format in your config.ini. Or create new custom settings with key: date.format and value: %d %b %Y
To use gtag.js. Create new key: google.gtag.id with value: your.gtag.id