I have similar problems, followed the instructions in the video and I can connect to http://172.16.42.1:1471/ from my mac(mountain lion). But then I turn on the internet sharing I can not connect to the pineapple anymore.
Then I tried with
# set
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkNumberStart 172.16.42.0
and then I turn on the sharing still the same problem. I get the following from ipconfig(en1 is the thunderbolt connection):
en1: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_HWTAGGING>
ether a8:20:66:27:d1:10
inet6 fe80::aa20:66ff:fe27:d110%en1 prefixlen 64 scopeid 0x6
media: autoselect (100baseTX <full-duplex,flow-control>)
status: active
bridge0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether ac:de:48:31:be:c1
inet 172.16.42.1 netmask 0xffffff00 broadcast 172.16.42.255
Configuration:
priority 0 hellotime 0 fwddelay 0 maxage 0
ipfilter disabled flags 0x2
member: en1 flags=3<LEARNING,DISCOVER>
port 6 priority 0 path cost 0
Any ideas what is wrong?