Disable Skype ads: 1.) Add hosts to your hosts file 2.) Flush DNS resolver cache (ipconfig /flushdns)

hosts

# On Windows 7, 8, 10 Hosts file is in c:\windows\system32\drivers\etc\hosts
#
# Block Skype ads

127.0.0.1 secure-sin.adnxs.com # On skype 7.*
127.0.0.1 *.adnxs.com # On skype 7.*
127.0.0.1 logi10.xiti.com # On skype 7.*
127.0.0.1 *.everesttech.net # On skype 7.*
127.0.0.1 pixel.everesttech.net # On skype 7.*
127.0.0.1 d.adroll.com # On skype 7.*
127.0.0.1 *.msads.net
127.0.0.1 *.msecn.net
127.0.0.1 *.rad.msn.com
127.0.0.1 a.ads2.msads.net
127.0.0.1 ac3.msn.com
127.0.0.1 ad.doubleclick.net
127.0.0.1 adnexus.net
127.0.0.1 adnxs.com
127.0.0.1 ads1.msn.com
127.0.0.1 ads2.msads.net
127.0.0.1 aka-cdn-ns.adtech.de
#127.0.0.1 apps.skype.com # keep this if you want to see Skype Home.
127.0.0.1 b.ads2.msads.net
127.0.0.1 bs.serving-sys.com
127.0.0.1 cdn.atdmt.com
127.0.0.1 cds26.ams9.msecn.net
127.0.0.1 db3aqu.atdmt.com
127.0.0.1 ec.atdmt.com
127.0.0.1 flex.msn.com
127.0.0.1 g.msn.com
127.0.0.1 live.rads.msn.com
127.0.0.1 msntest.serving-sys.com
127.0.0.1 rad.msn.com
127.0.0.1 sO.2mdn.net
127.0.0.1 secure.flashtalking.com
127.0.0.1 static.2mdn.net
127.0.0.1 static.2mdn.net

@BrendanJ: in my Windows 10 machine, the ads blocked without uncommenting it.

@StSav012: I didn't check the 127.0.0.1 static.2mdn.net, it's a remnant from original gist.
using ads2.msads.net will block the related ads but using *.msads.net not blocking any ads from ads2.msads.net. Looks like host file didn't work with * regex but I can't 100% sure about this.

I can't confirm the validity of those urls. Currently, didn't have any machine with Windows.

Removing the adds does not remove the add placeholder. This can be removed by going to: %appdata%/skype/YOUR_USER_NAME/config.xml and set all Advert values to 0:

      <AdvertEastRailsEnabled>0</AdvertEastRailsEnabled>
      <AdvertLargeEastRailCutoff>0</AdvertLargeEastRailCutoff>
      <AdvertNorthRailCutoff>0</AdvertNorthRailCutoff>
      <AdvertPlaceholder>0</AdvertPlaceholder>
      <AdvertSmallEastRailCutoff>0</AdvertSmallEastRailCutoff>

@RickR2H +1
@StSav012 +1

Working with only your instructions. Other hosts not needed