This is the translation of the Japanese Halo Commercial titled 'Mari'.
Below is the full Japanese script, english lines with translation, and
comments where applicable.

Japanese
====================
1. aa, kireii na.
2. uun.
3. yoku dekiteiru yoku dekiteiru.
4. uun.
[Elite scream]
5. aa, ima wa nani.

Translation
====================
1.  Ah, its pretty...

2.  hmm...
--there is no true translation for 'uun', it can be an affirmation, a
refusal, or even a filler word like 'uh..'... In this context, it is simply
a sound of awe

3.  It looks like the real thing...
--literally translated, yoku dekiteiru means well-done, but it is very
case-sensitive.  Since Marisan is observing a piece of artwork (the HALO
Skyline), it should be translated as "It looks realistic".  The phrase is
repeated to emphasize the statement.

4.  hmm..
[Elite scream]

5.  What was that, just now?
--this could also be interpreted as "Now what?"

The Japanese Halo Commercial titled 'Trans' does not have any spoken
Japanese, but there is a small caption at the very end..

" YABAI koto ni, nattekita. "

This can be translated into:

" It became a dangerous place. "
..... duh.. :|

The Japanese Halo Commercial titled 'Kyosiro' doesn't have any actual words. 
The player is making hideous noises, properly spelled "babababa..."  and
"kekekeke..." They are nothing more than childish sound effects.. "ba"
could be compared to "bang!", and "ke" is similar, but is often associated
with fully automatic firearms.  A machine-gun sound, I guess.   In between
the "babababa" and "kekekeke" is the not-so-fitting  sound of slamming a
clip of bullets into place...  Maybe he just doesn't like the sounds Bungie
made for everything ;)  Then there is the finale, in which Kyosiro displays
his wonderful artwork, stating the Katakana spelling of the letter X:
"Ekusu"...

Below is the japanese text, English translation, and comments for the
Japanese Halo Commercial titled 'Yamasaki'...

Japanese
===================
Iku wa yo...
[fires]
Hajikaretawa!!
Ei..
[fires]
Dou..
Ikaga?
Aa, mata deta!
[fires]
Wa, Naniyo!
===================

English Translation
===================
Here we go...
[fires]
It reflected!?
Hm..
[fires]
How..!?
How's that [bullet]?
Ahh! Another one!!
[fires]
Huh.. what!?
===================

As you can see, most of these lines are just things like 'huh' and
'what'... the player is obviously extremely confused about the whole
jackal-shield concept :)