As vensters and greg said, doesn't make much sense to me either that TI does the mirroring. I used a debugging proxy to see where the updates come from:
tracert download.windowsupdate.com
Tracing route to a26.ms.akamai.net [196.33.166.201] over a maximum of 30 hops:
1 1 ms 1 ms <1 ms Billion.400G [10.0.0.2]
2 8 ms 8 ms 8 ms dsl-146-208-01.telkomadsl.co.za [165.146.208.1]
3 9 ms 9 ms 9 ms rrba-ip-lir-1-gig-0-0-0.telkom-ipnet.co.za [196.43.8.198]
4 9 ms 8 ms 8 ms 196.43.25.138
5 9 ms 10 ms 8 ms internet-solutions-gw.telkom-ipnet.co.za [196.25.127.182]
6 10 ms 10 ms 9 ms csw4-rba-gi8-4.ip.isnet.net [196.26.0.249]
7 9 ms 10 ms 8 ms a196-33-166-201.deploy.akamaitechnologies.com [196.33.166.201]
Trace complete.
And a while later:
Tracing route to a26.ms.akamai.net [165.165.39.202]
over a maximum of 30 hops:
1 1 ms 1 ms <1 ms Billion.400G [10.0.0.2]
2 9 ms 8 ms 9 ms dsl-146-208-01.telkomadsl.co.za [165.146.208.1]
3 9 ms 9 ms 8 ms rrba-ip-lir-1-gig-0-0-0.telkom-ipnet.co.za [196.43.8.198]
4 9 ms 8 ms 9 ms 196.43.26.106
5 9 ms 9 ms 9 ms rrba-akamai-202.telkom-ipnet.co.za [165.165.39.02]
Trace complete.