Some of the last Nintendo Direct following around the world on Youtube, just Nintendo official channels
US
Pre E3 ND - 998.716
ND 06.21.2012 - 455.576
ND 10.25.12 - 89.321
ND 12.05.12 - 98.438
Pokémon Direct 01.08.13 - 521.029
Wii U Direct - 01.23.13 - 350.428
ND 02.14.13 - 297.924
ND 04.17.13 - 207.728
UK
Pre E3 ND - 1.872
ND 06.22.12 - 11.074
ND Wii U Preview 09.13.12 - 103.942
ND 04.10.12 - 13.976
ND 05.12.12 - 17.147
Wii U Direct - 01.23.13 - 23.095
ND 02.14.13 - 16.161
ND 04.17.13 - 26.282
For comparison, what I found about E3 conferences (Youtube channels of IGN and Gamespot)
IGN
Nintendo E3 2010:
Part 1 - 78.347
Part 2 - 58.021
Part 3 - 62.436
Part 4 - 48.882
Microsoft E3 2010:
Part 1 - 150.780
Part 2 - 85.646
Part 3 - 91.395
Part 4 - 60.260
Sony E3 2010:
Part 1 - 142.534
Part 2 - 83.792
Part 3 - 67.936
Nintendo E3 2011:
Part 1 - 369.336
Part 2 - 121.431
Part 3 - 103.521
Part 4 - 87.638
Microsoft E3 2011:
Part 1 - 749.790
Part 2 - 208.695
Part 3 - 143.644
Part 4 - 140.261
Sony E3 2011:
Part 1 - 621.165
Part 2 - 156.362
Part 3 - 128.974
Part 4 - 89.491
Gamespot
Nintendo E3 2012 - They had a problem with archives
Microsoft E3 2012 - 550.834
Sony E3 2012 - 478.025
Sony's NA 28M for the PS4 trailer
1.5M for See the future
1.3M for the Announcement
2M for Infamous
1M Killzone
1M Drive Club official channel
Sony's European channel (sonyplaystation)
PS4 Trailer - 358.950
PS4 - See the future - 754.121
Game trailer (Killzone, Drive Club, Infamous - 320.000 as highest
IGN Channel
PS4 Conference - 133.855