I thought to use rule like following to be able to impact only audio/video streams:

if(shExpMatch(host, "*.streaming.mediaservices.windows.net"))
{
	var host_ip = dnsResolve(host);
 
	/* Check if Stream services are targets */
	if (isInNet(host_ip, '72.21.81.200', '255.255.255.255') ||
	isInNet(host_ip, '152.199.19.161', '255.255.255.255') ||
	isInNet(host_ip, '117.18.232.200', '255.255.255.255') ||
	isInNet(host_ip, '192.16.48.200', '255.255.255.255') ||
	isInNet(host_ip, '93.184.215.201', '255.255.255.255') ||
	isInNet(host_ip, '68.232.34.200', '255.255.255.255') ||
	isInNet(host_ip, '192.229.232.200', '255.255.255.255'))
	{
		returndirect;
	}

    return proxyServer;                
}

Then I could minimize the DNS queries. And above code is just a snap, not full .PAC file 🙂