Basically you will need to create two sections (div elements) instead of just one, one for desktop and another for mobile. One section will have the current video shortcode provided by the theme. Another section will have similar content but the video shortcode will be replaced with a default embed code provided by the video site like YouTube/Vimeo. WordPress will automatically display the video if you provide the url to the video. Then, to control what gets displayed in what display resolutions, you can have custom css like this –
#desktop-section {
display: block;
} /* Show desktop section by default */
#mobile-section {
display: none;
} /* Hide mobile section by default */
@media screen and (max-width: 1024px) {
#desktop-section {
display: none; /* Hide for devices with lower resolutions */
}
#mobile-section {
display: block; /* Display in devices with lower resolutions */
}
}
Hope this helps.