for i in *.mp4;do mv -v "$i" ./$(echo "$i" | sed 's/[\ ,]/_/g');done

for i in *.mp4;
    do mv -v "$i" ./$(echo "$i" | sed 's/[\ ,]/_/g');
done

VAR=$(echo "$FIRSTNAME" | uniq | tr -dc '[A-Z][a-z][ÁáÉéÚúŐőÓóÜüŰűÍíäß]')

for i in *.mp4;do mv -v "$i" ./$(echo "$i" | uniq | tr -dc '[A-Z][a-z][ÁáÉéÚúŐőÓóÜüŰűÍíäß]';done