Hard to tell under that quality/focus. If it's got fine threads, definitely BBA. Odds are the coloration is from the right combination of PO4, NO3 and spectrum to encourage chlorophyll over carotenoid growth. BBA/audouinella is a very good example of algae that will change its pigment based on its growth conditions, and a great indicator of CO2.
If it's a solid blob, count on BGA/cyanobacteria. Better flow/surface agitation, blackouts and the right antibiotics will eliminate it quickly.
In both cases, you've got an algae that won't be a big deal once you know how to balance a tank. Unlike some of the finer innocuous hair algaes, diatoms and light GSA that become minor maintenance under good conditions, you shouldn't really have to see these around. One tuft of BBA or a spot of GSA usually sets off alarms after a while. Even GSA tends to relegate its self to the glass and perhaps hardscape after a while.
Yea PO4 seemed to take care of my GSA. I noticed it start to grow on the back of the tank glass and on a few leaves of my Alternanthera Reinecki. I added an extra days of dosing on PO4 and it started disappearing from the leaves and the glass. Not to mention the plant got a lot more red to it. But I did add a few cherry shrimp around the time I started extra doses. So I'm not sure if they ate it or if it was the extra PO4.