how can i read value in this field?

hi im so sorry im new in drupal coding i create video field and i use automatic video thumb in this filed for showing thumb image and i dont know how can i read thumb value b coz thumb store in this format:
a:6:{s:11:"video_thumb";s:101:"sites/default/files/video_thumbs/169/MV5BMTk5OTY4MDQ2OV5BMl5BanBnXkFtZTcwMjU1MDYxNw@@._V1._SY317_.jpg";s:21:"bypass_autoconversion";i:0;s:11:"description";s:0:"";s:10:"dimensions";s:7:"352x288";s:17:"player_dimensions";s:7:"352x288";s:16:"video_thumb_file";s:0:"";}
can we help me and show me how can i read this video_thumb's value by custom query b coz i dont like use views module for this work i need just custom query thanks alote.