Here's a review of the AVPlayerHD written by myself and i've also gone to great lengths in order to properly explain how to transfer files onto the iPad using USB cable and iTunes. I have to admit that since i've got my new iPad a few weeks ago, i've had huge trouble to find correct and detailed instructions on how to proceed with the file transfer. Unfortunately, it's not as simple as with Windows or Android, but once you get the basics down, it's not so complicated.
Review (also submitted and approved on iTunes for that app. Please vote for this review by searching for this app on iTunes and then click on "Most Recent" in the reviews list to find it, so that more people can read and learn from it. I really felt like i had to write this guide as it's much more complete and helpful than the other reviews for that app):
After doing a lot of research on the best iPad apps, this was my very first essential iPad app when i bought my new iPad 4th generation (iPad Retina) and it's a required app for anyone who would ever play videos on their iPad. It plays almost all video formats easily without any need for conversion. You just copy the movies to your iPad using iTunes and then launch the AVPlayerHD to play the video files.
After you've downloaded the app, here's a guide on how to copy any video to your iPad in the most efficient and fastest way: First, connect your iPad via USB to your computer and launch iTunes (make sure your iPad and iTunes are up-to-date, to avoid any possible complications/crashes/bugs). I am using the current latest iTunes 11.0. In the sidebar, find your device listed under Devices. If you don't see the sidebar, enable it; from the iTunes top menu, click on View -> Show Sidebar. You will then see your iPad name (whatever you have set in the iPad settings). Click on it (it has a small iPad icon to the left of your iPad name and a battery indicator to its right). Then, on the right, you'll see information about your iPad (Capacity, Serial Number, etc). In the same window, look at the top menu and you will see the following options; Summary, Info, Apps, Music, Movies, etc. Select Apps. You will see two main sections; Apps and File Sharing. Under File Sharing (with the following description: The apps listed below can transfer documents between your iPad and this computer), you will see the heading, Apps and Documents. In the list under Apps, select AVPlayerHD. On the right, under AVPlayerHD Documents, you will then see a list of all the files stored on your iPad which are immediately available to be played with AVPlayerHD. On the iPad, supported files are directly associated with a particular app, hence why you need to place all the files to be played with a particular app, in the latter's own folder. Initially, you will see this folder __InternalData__ which contains the installation files for AVPlayerHD, so do not modify its filename or contents. To copy your video files, simply drag and drop in that window space below that folder or you can use the "Add..." button.
You can also use the Wi-Fi Transfer option from the app, but it's much slower than using USB cable. The Wi-Fi feature in this app was unreliable during my testing (although that could be a port setting blocked on my router) and it didn't work for me, although the file transfer began and completed, it automatically restarted the transfer a few times before failing. In the Settings option of the app, i would highly recommend that you enable the Hybrid Decoder option to force maximum compatibility to play your copied video files.
To manage the copied files, launch the app on your ipad and use the Media Explorer option to play or delete the files. You can also delete the copied files by pressing the Delete key on your keyboard while having the file selected in iTunes in the AVPlayerHD Documents window. I've tried several media formats, and successfully played 720p and 1080p mkv files using the popular standard H.264 video codec and AAC audio codec. The playback was smooth. If you get any lag, check the app settings on your iPad. You can also forward or rewind easily without the audio or subtitles going out of sync with the video. Most subtitles work, when included within the mkv file or as a separate srt file, but the srt filename has to exactly match the video filename in order to be recognized by the app.
However, there is still a lot of improvements to be made in certain areas of the app; the playback of WMV HD format is far from perfect, since there is noticeable lag and audio goes out of sync. For some MKV videos, the subtitles are not displayed if the subtitle has special font, colour and shading. This needs to be prioritized in the next update of this app. The app should come with a pack of the most popular fonts used. On my PC, Media Player Classic Home Cinema has no trouble at all to detect and display the subtitles perfectly. Also, subtitles that use format tags, for example, tags used for italics, <i></i> are not supported, resulting in displayed subtitles with those tags showing. These tags should be parsed by the app, but this is another area of the app that needs more work. Other than those couple of specific problems, the iPad wouldn't be complete without this essential movie player app. It's way better than any other iPad movie app out there.