The second usage is quite literary and often comes off as awkward in normal conversation, where the use of intensifiers such as dữ, ghê, thế, vậy is more common.
For the first (and the only one common in colloquial Vietnamese) usage, the morpheme làm here often shifts to a syllabic nasal [n̩] in quick, colloquial speech. It can be assumed that làm reduces to *m̩ (see hôm in hôm nay and hôm qua) then spontaneously assimilates to the onset of sao.
