I’ve got the same issue, the problem is the plugin is detecting the device and loading a different code. Basically is calling the prefix vnd.youtube for android and iOS. Now the iOS prefix for youtube is just “youtube” so the solution is really simple:
youtube_shortcode.php ::: line 206
OLD
// Embedded Youtube player
if ($this->ios || $this->android) {
$link = 'vnd.youtube:'.$video_id;
// Link to Youtube's mobile site
} else {
SOLUTION
// Embedded Youtube player
if ($this->android) {
$link = 'vnd.youtube:'.$video_id;
// Link to Youtube's mobile site
} else if ($this->ios) {
$link = 'youtube:'.$video_id;
} else {