Perhaps it is this agreement SG's boyfriend was referring to. Although the source is Phnon Penh Post from 2006!!!

Southeast Asian countries agreed on July 25 allowing their citizens to travel within

the region for up to two weeks without a visa.

Most of the 10 members of the Association of Southeast Asian Nations (ASEAN) have

bilateral free-entry agreements with some or all of the members of the bloc.

But Vietnam requires visas for citizens of Cambodia, Myanmar and Brunei, and Cambodia

for citizens of Vietnam, Thailand, Brunei, Indonesia, and Myanmar. Philippines is

the only country in the regional grouping that does not ask for a visa from any citizen

from an ASEAN member state.

The ASEAN Framework Agreement on Visa Exemption will group the bilateral arrangements

into a uniform rule, allowing people of the region to visit member countries for

up to two weeks without a visa.
http://www.phnompenhpost.com/busines...asean-citizens