[FIX] web_editor: show proper video on existing video edition

See https://github.com/odoo/odoo/commit/5e38bef5a5ededb28707af44a19caaec2af2d682
and especially https://github.com/odoo/odoo/commit/45e0cd564afdae71e9525193250744e88076da71

Closes #19673

addons/web_editor/static/src/js/widgets.js

@@ -876,7 +876,7 @@ var VideoDialog = Widget.extend({
         this.$iframe = this.$("iframe");
         var $media = $(this.media);
         if ($media.hasClass("media_iframe_video")) {
-            var src = $media.data('src');
+            var src = $media.data('oe-expression') || $media.data('src');
             this.$("input#urlvideo").val(src);
             this.$("input#autoplay").prop("checked", (src || "").indexOf("autoplay") >= 0);
             this.get_video();