Perl - 177

while($d+=.1){print"\e[H\e[2J";$a=0;while(($a+=.01)<4*atan2 1,0){$x=$==40+40*cos$d+$a*$ARGV[0];$y=$==13+13*sin$d+$a*$ARGV[1];print"\e[$y;$x"."H#";}print$/;select($v,$v,$v,.03);}

The coefficients are passed via arguments. The above gif is produced from perl % 2 3