I saw police brutality but pretended i didnt should i have said something?

so i was @ a party last night there were a bunch of E pills being sold. cops came twice. the 2nd time they were liek EVERYONE OUT NOW blah blah they got all intense. lots of drunk ppl lots of high ppl. i however was completely sober, no drugs no alcohol. i was in the front yard & i was looking over the fence they were in some guys face "do u not speak english i said get the eff out" the guy is talking back the cop says "shut the eff up blah blah" the guy says u shut the eff up dont tell me that the cop right away puched him started hitting him w/ his baton (the guy didnt do anything wrong he was just talking back he wasnt getting violent or aggressive he was just sitting there) then they tazored him ppl started to crowd around & see then thay saw i saw. the police were like did u see anything to ppl who didnt see but were just accusing they were basically saying u didnt see anything so prove it. then it was all eyes on me i said nope didnt see anything. cuz its not my problem i wanted