How can I add View count and Subscriber Count?

When your showing script is modified, how about the following modification?

Modified script:

function youTubeSearchResults() {
  // 1. Retrieve values from column "A".
  const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const values = sheet.getRange("A2:A" + sheet.getLastRow()).getDisplayValues().filter(([a]) => a);

  // 2. Retrieve your current values.
  const modifyResults = values.flatMap(([keywords]) => {
    const searchResults = YouTube.Search.list("id, snippet", { q: keywords, maxResults: 10, type: "video", order: "viewCount", videoDuration: "short", order: "date" });
    const fSearchResults = searchResults.items.filter(function (sr) { return sr.id.kind === "youtube#video" });
    return fSearchResults.map(function (sr) { return [keywords, sr.id.videoId, `https://www.youtube.com/watch?v=${sr.id.videoId}`, sr.snippet.title, sr.snippet.publishedAt, sr.snippet.channelTitle, sr.snippet.channelId, `https://www.youtube.com/channel/${sr.snippet.channelId}`, sr.snippet.thumbnails.high.url] });
  });

  // 3. Retrieve viewCounts and subscriberCounts.
  const { videoIds, channelIds } = modifyResults.reduce((o, r) => {
    o.videoIds.push(r[1]);
    o.channelIds.push(r[6]);
    return o;
  }, { videoIds: [], channelIds: [] });
  const limit = 50;
  const { viewCounts, subscriberCounts } = [...Array(Math.ceil(videoIds.length / limit))].reduce((obj, _) => {
    const vIds = videoIds.splice(0, limit);
    const cIds = channelIds.splice(0, limit);
    const res1 = YouTube.Videos.list(["statistics"], { id: vIds, maxResults: limit }).items.map(({ statistics: { viewCount } }) => viewCount);
    const obj2 = YouTube.Channels.list(["statistics"], { id: cIds, maxResults: limit }).items.reduce((o, { id, statistics: { subscriberCount } }) => (o[id] = subscriberCount, o), {});
    const res2 = cIds.map(e => obj2[e] || null);
    obj.viewCounts = [...obj.viewCounts, ...res1];
    obj.subscriberCounts = [...obj.subscriberCounts, ...res2];
    return obj;
  }, { viewCounts: [], subscriberCounts: [] });
  const ar = [viewCounts, subscriberCounts];
  const rr = ar[0].map((_, c) => ar.map(r => r[c]));

  // 4. Merge data.
  const res = modifyResults.map((r, i) => [...r, ...rr[i]]);

  // 5. Put values on Spreadsheet.
  sheet.getRange(2, 2, res.length, res[0].length).setValues(res);
}

• When this script is run, the following flow is run.

  1. Retrieve values from column "A".
  2. Retrieve your current values.
  3. Retrieve "viewCounts" and "subscriberCounts".
  4. Merge data.
  5. Put values on Spreadsheet.

References:

• Videos: list
• Channels: list
• reduce()