Youtube Search RSS generator (deployable on Google Apps Script)

yt-search-rss.gs

function getSearchRSS(query){
  let results = YouTube.Search.list('id, snippet', {
    q: query,
    maxResults: 50,
    order: 'date'
  });
  
  let encoded_query = encodeURIComponent(query)
  let rss_url = ScriptApp.getService().getUrl() + "?" + encoded_query;

  let channel = XmlService.createElement("channel")
    .addContent(XmlService.createElement("title").addContent(XmlService.createText("Youtube Search RSS Feed: " + query)))
    .addContent(XmlService.createElement("link").addContent(XmlService.createText("https://www.youtube.com/results?search_query=" + encoded_query)))
    .addContent(XmlService.createElement("description").addContent(XmlService.createText("Youtube Search RSS feed for search query '" + query + "' updated on " + (new Date()))))
    .addContent(XmlService.createElement("link", XmlService.getNamespace("atom", "http://www.w3.org/2005/Atom")).setAttribute("rel", "self").setAttribute("href", rss_url));
  
  for(let i = 0; i < results.items.length; ++i){
    let video = results.items[i];
    let yt_url = "https://www.youtube.com/watch?v=" + video.id.videoId;
    channel.addContent(XmlService.createElement("item")
      .addContent(
        XmlService.createElement("title").addContent(XmlService.createText(video.snippet.title))
      ).addContent(
        XmlService.createElement("link").addContent(XmlService.createText(yt_url))
      ).addContent(
        XmlService.createElement("description").addContent(XmlService.createText(video.snippet.description))
      ).addContent(
        XmlService.createElement("pubDate").addContent(XmlService.createText(Utilities.formatDate(new Date(video.snippet.publishedAt), "EDT", "EEE, dd MMM yyyy HH:mm:ss Z")))
      ).addContent(
        XmlService.createElement("guid").addContent(XmlService.createText(yt_url))
      ))
  }
  
  
  return XmlService.getPrettyFormat().format(XmlService.createDocument(
        XmlService.createElement("rss").setAttribute("version", "2.0").addContent(channel)
      ));
}

function doGet(req) {
  let query = decodeURIComponent(req.queryString);
  return ContentService.createTextOutput(getSearchRSS(query))
    .setMimeType(ContentService.MimeType.RSS)
}

Awesome! Thank you so much. What an useful script!
Can you tell me how to incorporate a YouTube operator into the query? I would like to retrieve only videos longer than 20 minutes. I can´t get it running by adding ", long" to the query though.

EDIT:
I also tried adding the parameter videoDuration: 'long' to the results string (based on https://developers.google.com/youtube/v3/docs/search/list). However, it seems to have zero effect.