const regex = /.*\/videos\/(.*?mp4).*?(?<= )(\d+)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('.*\\\/videos\\\/(.*?mp4).*?(?<= )(\\d+)', 'gm')
const str = `https://videos-a.jwpsrv.com/content/conversions/7kHOkkQa/videos/JajSfbVN-32313922.mp4.m3u8?hdnts=exp=1592315891~acl=*/JajSfbVN-32313922.mp4.m3u8~hmac=d3ca7bd5b233a531cfe242d17d2ea0c0167b41b90fff6459e433700ffc969d69 19
https://videos-a.jwpsrv.com/content/conversions/7kHOkkQa/videos/Qs3xZqcv-32313922.mp4.m3u8?hdnts=exp=1592315940~acl=*/Qs3xZqcv-32313922.mp4.m3u8~hmac=c30e2082bf748a6b4d1621c1d33a95319baa61798775e9da8856041951cf5233 20`;
const subst = `$1 $2`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions