A modified version of this tutorial was originally posted on Good and EVO (my HTC EVO site).
With your Dell Streak and a couple of free apps, you'll never have to find out. Why? Because you can easily download YouTube videos and save them on your Streak's microSD card to watch anytime, anywhere.
There are two ways to do this: 1) using the stock YouTube app and 2) using a third-party app that ties into the mobile version of YouTube. The second option is more robust and lets you save HD versions of the videos, but you'll find instructions for both methods below.
1. Get YouTube Ripper from Android Market or scan the QR code below:
2. Launch the Streak's preloaded YouTube app.
3. Find a video you want to save and play it.
4. From the video playback screen, press Menu -> Share -> YouTube Ripper.
5. Press the "Rip It!" button that will appear beneath the box containing the video URL. You can watch the progress of the download by tapping "Downloads" at the bottom of the screen. Videos are ripped in standard quality and stored on your microSD card in an automatically created youtube folder (/sdcard/youtube).
1. Get TubeMate from Android Market or scan the QR code below.
2. Open TubeMate on your Streak.
3. Find a video you want to save, select it, and tap the "Save to" button on the playback screen.
4. If you're not already logged in, you'll be asked to choose between logging in or downloading. Choose whichever option you want.
5. A menu listing all of the video's download options, including HD if available, will appear. Choose your desired quality/format.
6. If logged in, you can save the video to your YouTube favorites list, an existing playlist, or a new playlist you can create in the app. The video will also be saved to the Streak's microSD card. If you're not logged in, the video will just be saved to the card. The default location is sdcard/Video but you can change it by tapping Menu -> Preferences -> Folder Setting.
You can watch the saved videos directly on your Streak, transfer them to your computer or another mobile device, or just hang onto them for safekeeping. Either way, you'll never be without your favorite YouTube videos again.