i have tired many times to download video form youtube, what is my problem
# youtube-dl -b
http://www.youtube.com/watch?v=ldB8kDEtTZA
[youtube] Setting language
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
[youtube] ldB8kDEtTZA: Format 22 not available
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
[youtube] ldB8kDEtTZA: Format 35 not available
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
[youtube] ldB8kDEtTZA: Format 18 not available
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
[youtube] ldB8kDEtTZA: Format 5 not available
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
[youtube] ldB8kDEtTZA: Format 17 not available
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
[youtube] ldB8kDEtTZA: Format 13 not available
[youtube] ldB8kDEtTZA: Downloading video info webpage
[youtube] ldB8kDEtTZA: Extracting video information
ERROR: no known formats available for video