サムネイルの種類

120 × 90

http://i.ytimg.com/vi/HgB0T1NIJcY/default.jpg

http://i.ytimg.com/vi/HgB0T1NIJcY/1.jpg

http://i.ytimg.com/vi/HgB0T1NIJcY/2.jpg

http://i.ytimg.com/vi/HgB0T1NIJcY/3.jpg

320 × 180

http://i.ytimg.com/vi/HgB0T1NIJcY/mqdefault.jpg

480 × 360

http://i.ytimg.com/vi/HgB0T1NIJcY/hqdefault.jpg

http://i.ytimg.com/vi/HgB0T1NIJcY/0.jpg

640 × 480

http://i.ytimg.com/vi/HgB0T1NIJcY/sddefault.jpg

最大

http://i.ytimg.com/vi/HgB0T1NIJcY/maxresdefault.jpg

存在しない場合

http://i.ytimg.com/vi/HgB0T1NIJcY/aaaaa.jpg