7
C (GCC/linux), 402 353 352 302 300 298 296 288 bytes
#define R rand()%
x,y,w,h,r;main(c){srand(time(0));scanf(
"%d%d",&w,&h);for(printf("\e[2J");x%~w*
(y%~h)||(c=R 8,(r=R 4)&1?x=1+R w,y=r&2
?1:h:(y=1+R h,x=r&2?1:w));usleep('??'))
printf("\e[%dm\e[%d;%dH\342\224%c\e[H\n",
30+c,y,x,2*"@J_FHAF__L@H...