code: function validCustomTag(tag, attrs, lkey, value) {
        // catch the div placeholder for the iframe replacement
        if (tag === 'img' && attrs['ta-insert-video']) {
            if (lkey === 'ta-insert-video' || lkey === 'allowfullscreen' || lkey === 'frameborder' || (lkey === 'contenteditble' && value === 'false')) {
                return true;
            }
        }
        return false;
    }
docs: this function is used to manually allow specific attributes on specific tags with certain prerequisites