Some idle soul has done the world a favour by amalgamating wartime newsreel clips from the British Pathé and Japanese NHK archives.
As the running time is quite substantial, what follows is a breakdown of the bits of most interest to wargamers (not that the rest isn’t worth watching, particularly for those wishing to see a leafy Bangkok unsullied by today’s congestion):
00:04 Primary school members of the Yuwachon youth movement participating in irredentist marches.
0:54 Arrival of a Laffly S15R bearing Japanese mediators.
00:59 French troops, including one cheeky-looking chap in a non-regulation beret.
01:42 Thai reservists presenting arms to the Franco-Thai-Japanese armistice commission.
01:51 Thai Madsen team.
02:13 Thai victory parade on Ratchadamnern Avenue.
02:24 Infantry contingent.
02:59 Ford AA trucks towing Krupp mountain guns.
03:10 Vickers 2pdr carriers.
03:16 Carden-Loyd tankettes.
03:23 Ha-Go tanks.
03:58 Japanese troops enter Bangkok.
06:15 Victory Monument opening ceremony.
06:40 Thai army marching band.
07:05 Thai troops in full field uniforms.
07:23 Navy sailors.
07:32 Yuwanari members of the Yuwachon movement.
14:40 Arrival of Japanese Prime Minister Tojo at Don Muang airport.
16:39 Vickers 6-Ton tanks.
17:06 Thai navy marines.
for a few rounds more 
Great blog! Thanks for posting very interesting documents and material, and entertaining and trustworthy comments!
Merci!
Nicolas Rey-Coquais
(Phitsanulok)