Vinod's chords sound fine.
You could play Gm6, Gm7 and C6 in some places to include the melody note.
Gm doesn't really 'fit' in many places (C in some) throughout the song, but still used just for the sake of chord progression (I think!). Maybe someone with a bit of music theory background can explain.
(Dm)Maayam seidhaa(Bb)yo, nenjai (Gm6)kaayam seidhaa(C6)yo
you gotto do it.
(Dm) Kolla vandhaa(Bb)yo, bathil (Gm6)solla vandhaa(C6)yo
you gotto do it
(Dm)Vaari chendraai pennai, (Gm)parthu ninren (C)kannai
(Dm)Yedhu seidhaai (Bb)ennai (Gm)kettu ninren (C)unnai
(Dm)Naan chedi valarum (Bb)thoottam aanen
(Gm7)Yaanai vandhu pona (C)sollai aanen
(Dm)Kaadhal karai purandu (Bb)oda paarthaen
(Gm7)Thoondil mul nuniyil (C)uyirai korthaen
(Dm)Minvisiri kanvisri vegu thooram (Gm6)vilundhen(C)eeee
(Dm)En perai naan ma(Bb)randhu kal pola (Gm)kidandhaen(C)
Stop existing and start living!